tf2 guide:
Medic: fun class when you have a good team.
Soldier: win button.
Heavy: boring win button.
Demoman: spam button.
Sniper: pretty fun class. too many people choose it.
Spy: no skill DR spam. annoying class. too many people choose it and suck at it.
engie: frustrating and boring class.
pyro: too hard to play. really underpowered.
scout: good for sneak attacks.