TBH I don't reallylike FPS, And I really don't like multiplayer, unless it's local with friends. if it's not awesome (or have role-playing elements. i think it's boring)
1. Deus Ex
2. Half Life 2: Episode 2 (and Half Life 2) (half life 2 episode one was bleh)
4. Perfect Dark
In no order
Jedi Knight II
Deus Ex 2
Team Fortress 2 (Yes, the exception to the rule, though I still don't play it that much)
Really though, if it came down to just shooting mechanics I'd half to take Deus Ex, Deus Ex 2, and Bioshock.
BioShock? That game had non-existent RPG elements, it was more of a shooter than System Shock 2.