Well obviously any USCM fan would want the rest of the movie characters. I'm a realist though and we'll probably see Drake and that'll be the end of it. Maybe re-issues of Hicks/Hudson and Vaz if that new anniversary Ripley with the new HS tech does well.
I say ACM because gear wise they're just about 100% identical to the movie marines and since I'm an army builder they have the most appeal. It has nothing to do with the actual characters so much as "ah, this smart-gunner has tattoos, thats unique but also fits in with the marines I already have". Same goes for AVP2010, while not as close as ACM they're close enough and just seem the natural progression of USCM tech. I'd buy just about anything from AVPE mind you, I just have a personal preference.