Well, with all the talk of the Chaos army being split into multiple codices (Daemons not counting), I don't really want to have to buy 3 books, collect figures from all of them, and then get told I can't play in a tourney with them. So, as of now, I am going to start collecting my appocolypse army (30,000 points of Guard, mostly artillery) and wait with Chaos until I see what is going to happen with them. I have seen this song and dance before, what with
WHFB, and don't want to.... repeat past mistakes.
I really like Chaos Space Marines, don't get me wrong, and I might even decide to stay with them, but still want to have a "Fallback" army that is less likely to split into three on me. These are the ones I am considering (not really taking in competativeness, just funness):
Orks: Who doesn't like Orkses? I have been looking at making a Savage Ork themed army, with lots of boyz, Wierdboyz, few vehicles, and red warpainted Orks (would that give them an extra inch movement?

)
Tyranids: Bug eyed monstrous creatures, and a battlefield littered with multi limbed bugs are always cool. Probably just a standard Nid list here.
Necrons: Unfeeling machines that would be relatively cheaper to collect than the other two choices. Only problem is that is what their missing, Choices. Not a whole lot you can do with Crons, other than a cool paintjob.