I've been playing a lot of Engineer lately. Aside from the fact that I have to be the one to blow up vehicles, the RPG is actually an insanely powerful weapon against normal people. It's an instakill with a big radius and a potentially very long range, I've sniped snipers with the RPG and got some hate lol.
Also the engineer can use semi-automatics which are great. The M110 is my favorite weapon in the game so far.