i am always a support class, weather it be a medic healing everyone to a sniper (yes its a support role) taking down those annoying targets.
In resistance 2 i like medic, if not that then spec ops.
in tf2 i like medic, engineer and sniper.(pyro when im annoyed to hell)
IRL i play airsoft, im the guy that is decked out with guns, in a gullie suit, and shooting you in the back.
I have an M4 (full auto) for accuracy, a g3 (full auto) for supporting/suppressing fire, and a m1191 ("pump" have to cock it evry time) pistol as a secondary.
I will sneek behind the enemy, no matter how long it takes, take a hostage and use him as a meat sheild, and cover his mouth so no one hears it, then gun everyone down.
EDIT: In games that have anykind of transport vehicle i might uses that, especially a helicopter.
In bf:bc i always use the helicopter because I am a FENOMINAL pilot, i can fly at 2 feet or 200 feet it doesnt matter, im the best damn pilot you'll find on the battlefeild.
in bf:bc 2 when it comes out I will ALWAYS be driving the black hawk helicopter transporting troops in and out of the battlefeild, hopefully they give us the parashute back because that will be very helpfull.