mine is:
1) Crysis
2) COD4
3) Bioshock
and hear are my reasons: Crysis comes first because A) it look very nice B) its perfectly playable, not sure what your'll all doing with your systems C) the single player is reasonable length and quite an interesting story to be honest D) nanosuit is a nice change from most other generic FPS and finally E) customisable guns, again a nice change, so many crysis haters on this forum, never understood why since there arguments are pretty weak, especially when COD4 gets so bigged up. another thing in crysis favour is the game comes with the sandbox2 editor which you can use to create your own levels and such, though its pretty difficult to use
COD4 comes second because it A) looks reasonable good B) plays fluidly throughout everything C) feels polished, the things letting it down IMO are A) the single player story is weak and short, i mean FFS extremists, i see enough rubbish about that on the news everyday or in the paper B) its so unrealistic it hurts C) the weapons are pretty generic and sound pretty generic D) the multiplayer even though its SOOO well regarded im sorry to say is just another generic FPS MP, deathmatch, etc.
Bioshock comes last because A) it gets old so fast its not funny, you get to a point where you have certain plasmids and no enemy is particularly difficult to kill, not even big daddies B) rapture although stunning at first sharp starts looking like the same thing over and over, things in its favour IMO are A) it looks very good, better than COD4 but not as good as crysis B) it runs well, without slowdowns or anything on mid-range hardware and C) the interface is very well engineered, managing weapons and plasmids is very simply and painless