Salmon class for me, I think... whichever one I'm in now
It looks so damn sexy... like a sleak killing maching of death.
There's alot to chose from, I've only tried 3 (Gato, Salmon and Porpoise) but the career I've settled on for now is the Salmon.
Ah, the big reason is the AA gun view isn't bugged on the Salmon class, this was a big thing for me as I do enjoy failing to shoot down planes