Weapons- Insomniac's big thing has always been crazy weapons, so I have no doubt they will deliver in that category. In Left 4 Dead I've only seen shotguns and machine guns, but I don't think that is really the game's selling point anyway so: Resistance 2
Enemies- Zombies are cool; not that it hasn't been done before, but things might get boring aside from the giant bosses. The Chimera are an alien race so there's a lot more room for new enemies and innovation. I'm especially liking the 300 ft. Leviathan.
AI- From a technical perspective Resistance 2 would win because of more sophisticated individual AI patterns, but the spawning system where enemies pop-up behind you and where more enemies focus on particular players sounds really cool. Left 4 Dead
Art Direction- Resistance's 1950's America mixed in with Chimera architecture is interesting, but the screen effects Valve is using (grain effects, washing out the color) makes the game seem as though you are really in a zombie movie. Left 4 Dead
Replay value- Resistance 2 has a 60 player online that uses 6 man squads to keep things controlled - and you can still play ranked games as small as 3v3, an 8 player online co-op with classes and randomized geometry to keep the levels fresh, a single player
campaign and a split screen co-op.
Graphics- once again from a technical persective it would have to be Resistance 2.
Sales- As far as console sales go I think it would most likely be in Resistance 2's favor but I'm not sure how many units will come in through steam.
Overall- I'm going to have to say Resistance 2 mainly because I love Insomniac games and I know more about it.
