That's a great summary Julia and aligns with "conventional wisdom" on the topic (so many threads!). I just have a couple of things to say in response:
- Lurker certainly does have some issues (Miskatonic helps a bit) but you get the Lurker Gates! In my opinion, these are as valuable an addition to the game as the Injury/Madness mechanic from Dunwich and you get them for the cost of a small box. You also get Relationships. I like Lurker.
- Dunwich can be played with the Dunwich Horror herald from Miskatonic (and downloadable?) and that adds even more legs to an already great expansion
- Do not underestimate the value that Personal Stories from Innsmouth bring to the game. Julia mentions (positively) them in passing, but they really do add a personal motivation for each Investigator and that helps you "invest" in the Investigator you're playing
My recommendation would be to first buy either King in Yellow or Dunwich Horror, then buy the one you didn't buy first and then buy Lurker (for the Gates). After that I'd go for either Kingsport (if you're looking for "more") or Innsmouth (if you're looking for a beating). Then you'll just buy all the rest anyway because you'll be hooked. My ideal "standard game" for people wanting to move beyond base game would be Arkham + Dunwich + Dunwich Horror Herald + Lurker Gates + Innsmouth Personal Stories. My group played this way for a long time before we felt the need to move on to playing Innsmouth.