Medic, I am always one to help before fight and I am rather good with him; however, if we are talking strict personality, I would have to say the Scout, though I do no share his pention for violence, I do have the same ego problem as him, and if left undeflated, it does get that bad.
Yesh, I am a Pyro, almost always. They are a fun class to play, and are all about getting up-close-and-personal with their enemies. And burning them. They also have a fire axe with barbed wire wrapped around it. I mean, seriously! How cool is that?!
EDIT: Forgot to say: My secondary class is a Medic, and after that I choose sniper.