which game is better?.

mass effect 2 or bioshock 2?
which one of those is better?

If you want a much better single player game then ME2, If you want a decent single-player and surprisingly enjoyable Multi-player then Bioshock 2

I wouldn't agree about the multiplayer. It's capped at 35fps for the p2p, it was fun for the 3 or so goes I had but you can't play like that. I haven't played ME2 so I can't comment but I'd say go for that, bioshock isn't all that great, just more of the same, pretty meh.

Haven't played Bioshock 2 yet. But I'll probably like Mass Effect 2 more.

ME2 FTW !!