M9K CW 2.0 or FAS?

Definitely FAS weapons. M9K weapons are good for non RP gamemodes that rely on typical fast paced fire fights, however FAS is hyper realistic and requires aim to properly use. Spraying someone from afar with FAS won't get you far, it forces players to scope in and make use of semi automatic fire. Also a good MRDM stopper. CW is good, but I don't feel it has the versatility that FAS has.

Source: I use FAS on my servers and it does a mighty fine job.