I prefer Team Fortress Classic
Cept Source doesn't feel like CS. It feels more like deathmatch. The hitboxes are absolute trash, I see people shoot at someone's stomach and get a headshot with an mp5 (doesn't spray upward like the AK), it's BS. But its still very fun regardless. Cept there's way too much environment noises, can't hear footsteps at all.
TFC is king as well. Have you guys seen Fortress Forever? TF on the Source engine...*drool*. google it and check out the website, the progress looks very good.