1) How vital are the expansions?
2) how complicated is TI3 compared to AH & BSG?
3) how easily can the components be condensed and stored?
4 and final) if you had to rank TI3, AH, and BSG in order of which is more fun for a group of four, what would it be?
1) In my opinion, expansions are vital to make the game fun, variable, in some regards playable. In any case: You DO want them, if you want TI:3
2) Since you have a lot of AH-expansions, compared to that, there are much less rules. It's just a pretty chunk at once. I advice taking all the rulebooks and FAQs, and condense them into one neat simplified pack of data. It also helps memorize it all. Doesn't take that long even
TI has more core-rules than AH, but much less special-case rules, even with the expansions.
3) Difficult. I have two magazines with plastic cupthingies. Where I needed 2 per Fleet, and 1 per race, in which I stored Markers, and all race-speicific counters and cards (including home planets - really guys, it makes sense to put them to the races! You never need them in the planet-deck)
And then a few others for all the other cards and counters… It's around 40-45 I'd say with the current system. I'm still looking for something better though.
4) For a group of 4 I would probably prefer AH. Personally I think about TI:3:
3 players: playable, but rather militaristic
4 players: starting to work, but mostly ending in 2 on 2s
5 players: the fun begins.
I can't say anything about BSG though, sorry.