I'll generally call the ship I main Nautilus on all my toons, mainly because I'm a fan of 20,000 Leagues Under The Sea and I've always preferred Trek ships when they were at their most "space is an ocean".
Heavy Escort Carrier - Nautilus
Patrol Escort - Dalek Saucer (I'm a Doctor Who fan and I can my the patrol escort almost look like a flying saucer)
Excelsior - Poseidon
Assault Cruiser - Hyperion
Advanced Escort - Triton
Odyssey Star Cruiser/Star Cruiser - Behemoth
Defiant - Phantom
Galaxy-X - Valkyrie