Sniper
Dragonov
Desert Eagle
Flash
Claymores
UAV Jammer
Iron Lungs
I like the Dragonov because I have yet unlocked the Barrat 50 Cal

I have the R700 I think it is, but I don't like Bolt Action Snipers.
I love the Deagle, and I have found myself just running round getting kills with that.
Claymores, People are just stupid to not see them and run straight into them...so many kills

I find UAV Jammer important so you don't get counter sniped, whiched happened alot when I didn't have it.
Iron Lungs help alot for aiming.
Ghost
P90 w/Silencer
Deagle w/Silencer
Smoke
Frag x3
UAV Jammer
Dead Silence
However much people hate it, I love the P90, and with silencer your just about invisible on the radar. Same with the Deagle
Smoke, I find, gets me places easier because you can go unseen
Frag x3, well I just find it gets me more kills
UAV Jammer so that you are again just about invisible
Dead Silence Gets me around without being detected.
I can only remember these 2 classes because I have extremely bad memory, seriously. My username is my Gamertag and I play alot of Team Deathmatch (not hardcore) but if you add me I'll tell you now I play alot of Madden '09, NFL Tour (and I'm english :P) and Skate 2, but I am on Cod4 alot