What are the best FPS multiplayer games?

The only games I play online are Call of Duty UO and Red Orchestra Ostfront.  I've tried Battlefiend 2, Battlefield 2142 and Call of Duty 2 but just didn't like the gameplay. 

What multiplayer FPS do you reccomend? 

Try Counterstrike 1.6, Counterstrike Source, Day of Defeat, and Day of Defeat Source.smokeydabear076

I was leaning towards Counterstrike since I'm currently playing Half Life 2 and like the gameplay. 

What's the difference between Counterstrike and Counterstrike Source?Zman68

you didn't like BF gameplay and you like CoD - then try F.E.A.R. Combat - free game to download and play

and CS: S

Counter Strike, FEAR[QUOTE="Zman68"]What's the difference between Counterstrike and Counterstrike Source?oscar530

you didn't like BF gameplay and you like CoD - then try F.E.A.R. Combat - free game to download and play

and CS: S

PredatorRules

where cani download this game F.E.A.R Combat??