I'd dare to say COD4 even without having played Resistance.
Of course I'm not entirely serious, but I do know that a lot more people think COD4 is a lot more fun, and that it is the best 'generic' FPS I have ever seen (yes I've played it - who hasn't?). Call of Duty's atmosphere, realism, and perfection are just too good for any FPS game to compete with (more story-driven, non-generic games like Bioshock except).
I drink your milkshake.