I'll just make rather limited suggestions based on my proposed "dream team" but bear in mind your Overlord, quest routes and playskill matter. Play what you understand and like to play.
 
Alvric as Disciple
As I said, Cleansing Touch is a nice cheap skill that is useful all game. Removing conditions is very handy and while it shouldn't be necessary to win, it can prevent you from losing tempo with the Overlord. I'm fond of Divine Fury and Holy Power. You can't overlook the usefulness of more power dice and healing for no increased fatigue cost.
 
Widow Tarha as Runemaster
Exploding Rune is too useful not to get as soon as you can. It is damage multiplication that forces the Overlord to play carefully. Honestly, the rest of Runemaster is based on what you need. Like the Disciple's ability to remove Conditions, the Runemaster's ability to apply them with Runic Sorcery is handy, but for the exp and cost it is rather expensive. Don't overlook anything in the Runemaster kit. I've even seen heroes make good use of Break the Rune.
 
Jain as Wildlander
Danger Sense can determine an entire Campaign. Overlords will hate you for spamming it. You can actually starve an Overlord of cards and really ruin his day. It actually feels like cheating and you kind of feel dirty afterwards. Wildlanders have amazing bow synergy. Keep an eye on passive bow-enhancing effects like Accurate, Eagle Eyes, Bow Mastery and Running Shot.
 
Syndrael as Knight
Advance is too good not to take as soon as possible. It is movement and an extra attack when you get a kill. Challenge is also a useful 1-exp skill that lets to pump out more damage on a single target each turn. Both of Knight's 3-exp skills are quite good, Stalwart and Inspiration. All the skills I haven't mentioned are useful but will need your personal judgement if they will be of use that Chronicle.

If its any help, I have a page on my site that shows the most used skills/items for each class. Keep in mind, this is just based on usage, it does not mean they are the best. (For example, Leoric is so popular as runemaster partially because he is in the Base game. Not everyone buys expansions, so those base game heroes get used way more often)
 
Anyway, it might give you at least an idea of what you should/could look at.
http://d2etracker.com/stats_class_page.php?class=4

I'll chime in.
 
I don't own Lair of the Wyrm yet so I can't say what is more useful for those quests, but for The Shadow Rune overall reliability with some mobility is most useful.
 
Healer
Character: Based on what's available to you, Avric Albright is the more useful of the healers.
Class: Disciple heals a little better and removes conditions while Spiritspeaker can do damage decent damage and prevent lots of damage with Cloud of Mist. Both are good choices but expose different weaknesses.
 
Mage
Character: Widow Tarha and High Mage Quellen are both selfish Mages. If you just hate missing, go with Tarha. If you want to make big plays go with Quellen. Leoric of the Book's passive can be very powerful if utilized well. There isn't really a wrong choice.
Class: Runemaster is arguably the easiest and most powerful. Geomancer is a good option too. Geomancer's high fatigue costs mean you probably want to synergize with Quellen.
 
Scout
Character: Jain Fairwood is arguably better than Tomble Burrowell.
Class: Thief is just harder to use well compared to Wildlander. You cannot go wrong with Danger Sense.
 
Warrior
Character: If you didn't bring the Disciple, you may want Grisban the Thirsty since he can shrug off Conditions. Again, if you just hate missing Reynhart the Worthy is a good choice. Finally, Syndrael's Heroic Feat is arguably the best of the three. That mobility is game-changing.
Class: Barbarian can break the game with his damage but is easily played around by the Overlord. The Knight is a mobile fighter with extra-attack mechanics which isn't bad. The Champion is more of a "team-player" that can enable other team members to shine but likely won't carry a game like either of the aforementioned warriors. None are a poor choice but pick one that suits your playstyle.
 
My dreamteam with what is available to you would likely be:
Alvric as Disciple
Widow Tarha as Runemaster (I have issues with misses)
Jain as Wildlander
Syndrael as Knight

I wish to only speak for myself here, but the "big deal" is that I enjoy the game the way it is ... not the way FFG describes the game will play with the app.  I say this, however, without having played with the app as of yet.  I want to give it a go first, before making a final decision.
 
Now, you, and many others will say, "... fine, don't play with the app".  And I agree.  We will have that option.  For existing content.
 
The issue for many who feel as I do, however, is a concern that the following is true:
 
ALL FUTURE CONTENT WILL ONLY BE DEVELOPED DIGITALLY FOR THE APP
 
No one from FFG has made this statement.  We don't know if it is true or not.  If not, and if FFG continues to develop expansions for the game, all well and good.  Both sides of this "issue" remain happy.  If, however, the game does not continue to be developed as it has in the past, including physical expansions both large and small, but instead just has digital content made for the use of the app, then I, and many others like me, will be decidedly unhappy.  This is especially true for those of us who have purchased each and every expansion for this game, and thus have a substantial investment in the game.
 
Hopefully I have made my position clear.  I am happy for those that like the prospects of the app ... I am also pleased by it.  I just don't want to simultaneously lose new content for the way the game currently plays.
 
*** The Big Deal *** -- Quite frankly, compared to many issues facing all of us in our world today, this doesn't even qualify as a blip on the radar of real world issues.  

Yeah, I bet FFG put zero thought into that when they designed this game mode. I bet this thread is causing a complete app redesign (hence why it's taking so long) as we all hash out our emotions on this topic on the internet and enlighten them on what a mistake they've made. They should really learn how to design a game..
 
 Wait, what?
 
15 pages of rampant pessimistic speculation and criticism of a completely optional game mode that no one has any real details on other than a teaser article, and that is, depending on who you listen to, going to break everything balance-wise or possibly take the product in the wrong direction, or alienate some players, or render entire heroes useless or... bah whatever. Now it's starting to rub off on me. For shame. Other than some high-level details we know squat about how it plays on a real table. Please, tell me more about how FFG has no idea what they are doing to their beloved D2E or they're doing it wrong, all based on complete conjecture. When this thread gets to 25 pages remind me again how they are headed the wrong direction with the game. Oh wait, how many threads around here lately have had this many pages in such a short span? On community energy-level increase alone they are already winning. How many have chimed in on this thread to state they've made purchases of D2E content to round out their collections in anticipation of this exciting development, usually after wiping a thick layer of dust off their game boxes from non-use because the game in it's current state wasn't doing it for us anymore.
 
FFG: do your thing. Take our money. There are those of us that have been waiting for something exactly like this and we trust you know a thing or three about designing a game/expansion. We will reserve judgement until we actually have something to judge.

My two favorite tactical grid-based games are the Fire Emblem series and Final Fantasy tactics. One has a player - enemy turn system, while the other determines turn order based on the 'speed' of individual characters. Though they require different playstyles, I enjoy them both very much. But because they are different, it is hard to compare. Or as we Dutch say 'comparing apples with pears'.

Because they want to play what they want to play. Simple as that and no further justification needed. Who are you to question the validity of other peoples' play preferences? Who made you the king of what is right and what is wrong in gaming? You do realize that there was a time when Role Playing games were pen and paper only, right? And there were alpha gamers such as yourself that scoffed at a product like Warhammer Quest and even Descent. "What??? It has map tiles pre made? You can't do that! The only way is to make your maps on graph paper and your imagination! And the dice dont have numbers? Theyre only six sided??? No D20s? No percentage dies? They are dumming it down (sound familiar?). They're ruining gaming!!" Well, it's called innovation. Product evolution. Market development. It's how new and cool things come to be. And guess what? The old pen and paper rulebooks and modules are still available on the market today, stronger than ever and in more variety than ever.
FFG recognized how a sizeable but silent segment of their consumer base were not being properly served and they came up with a great idea and product to address the reasons why they dont play Descent more often and to make them happy too. At absolutely no consequence to gamers like you. You play how you want and let me play how I want. If we could all follow that one mantra, I think the world would be a much better place. No?

That is the beauty of this, they are making this off existing content and still have physical expansions coming down the pipeline for the traditional game mode.  This is a FREE app with a nominal purchase of $9.95 for a full length campaign.  They are basically doubling the content of the stuff you have already bought.  And people still find a reason to complain, lol.  It just goes to show you truly can't please everyone and some personality types just love the friction.

hey guys! just wanted to chime in about how excited I am for this app... it's so great to have an official coop expansion of sorts that finally uses the huge stack of stuff I already have for Descent!!

FINALLY!! I have been collecting every expansion to date but, aside from the 3 solo quests offered, the entire collection has sat dormant because I have no other folks interested in playing. Now everything is unlocked for me to play solo! I am beyond ecstatic! I'm assuming you will still need to use the physical cards and dice? Though these things could be generated through the app. I do hope they keep the requirement of all the physical pieces of the game. Protects the IP as well. I can't wait for this. Let's hope it a a legit tool that unlocks the power of the physical product that you have pur hased and not a way to introduce micro transactions to our beloved game.

What I prefer in D2 co-op with respect to D&D is the fact that when you enter a new room you have a "plot": the room tells you what you have to do (the "objective" for the room) and this is different for any new room. In D&D you enter and you have monster(s) to kill. That's it and, to me, this is a missed opportunity.
 
This to me is the most important part in a dungeon crawl.

am I the only one getting a bit annoyed by little packs of cards for 15 bucks with so-so replayability?
 
the small expansions are 40 bucks and give you minis, map tiles and new functionality. the big ones are 60 dollars, which is the price for 4 pod packs.
 
I'd rather prefer ffg would do a proper full fledged campaign in a box...

Co-op Descent is (and should be) the future

always

i want a full expansion with solo/co-op , constant level up, and more exploring. 

Simple :-)
 
Co-op (GNK) is dungeon crawling
 
Descent2  is a tactical game (for me 2 heroes vs. overlord is unplayable and 3/4 heroes for one player is overwhelming) and the campaign will take an era to be played (at least 9 playing sessions).
 
So if you look for a dungeon crawling game, GNK is the solution, but needs a little more variability for replayability. We (my wife and my two nephews) played it twice in four days (half a campaign per day) and it was exactly what we were looking for.
 
I can understand people wanting a tactical game (I prefer Go), but it is a pity for us looking for a dungeon crawl to have so much (in terms of "great material" (heroes, monsters, items, tiles, ...)) and cannot use it for a "simple" dungeon crawl. GNK is so much better than D&D board games (CR, WoA & LoD). I hope FFG will not miss the opportunity (use the same material for two different ways of playing getting both markets).

Co-op Descent is (and should be) the future

Sure thing. it's been a while, so it's probably way down there in the files section.
Here's the link: http://www.boardgamegeek.com/file/download/n23ga5voj4/D1E_Basic_Conversion_Rules.zip