Here is what I would use for a Earth Alliance shipset. Some of the ships below are from Agents of Gaming's Babylon 5 Wars. You can get pics of the miniatures at
http://www.agentsofgaming.com
ES: Tethys Police Cutter
FG: Artemis Frigate
DD: Olympus Corvette
CL: Sagitarrius Missile Cruiser
CA: Hyperion Heavy Cruiser
BC: Nova Dreadnought
BB: Omega Destroyer
DN: Warlock Destroyer
CVL: Artemis Light Carrier
CV: probably a carrier variant of the Omega
CVH: Poseidon Supercarrier