Personally I'm more of a sniper. I have good aim and there's something about being a shadow, killing everyone before they can tell where I am.
That said, however, I like almost any weapon, and am known to often pick an M3 shotgun or P90 SMG over the MA14 or AK47 in CS:S.
I also dislike being a "campy" sniper...You know, the kind of guy that just sits in the same place for half an hour shooting people... I think I was possibly the first, or one of the first, "rushing snipers" in Day of Defeat Source...Nobody saw it coming either... While all my allies with machine guns were getting mowed down, I rushed through with a sniper, killed everyone in the process, and after running out of bullets proceeded to hold the place for about 2 more respawn waves with my pistol... We won that one...