What are some good online FPS games for PC?

i have battlefield bad company 2, crysis 2, AVP, and left for dead 2, i also had dead space but i didnt enjoy that too much. i have played and finished the halo saga. is cod any good on pc cause my friend hates it unless its on a platform and hes a pc gamer. what are your suggestions for good online FPS? i dont mind paying up to $80-100 on steam or ea, but i dont want a low budget game, something in the middle would be ideal