From the early GAMEPLAY videos I have seen of Killzone 2, it seems to be really intense and amazing. The only compliant being the AI. No doubt the AI has improved over the last year, so it should turn out to be a really good FPS.
Although we haven't seen much of Resistance 2 (just the teaser video), we do know that Insomniac have a great record for producing top class games. Also 8 player co-op and 60 players online sounds like a lot of fun.
It is difficult to choose between them, but at the moment I am leaning towards Killzone 2.








