If you have 3000 zen you could probably add lobi ships to the options.... you can probably generate 60-90 million ec with zen purchases being listed on the exchange. That would open up the galor, d'kora, the monbosh, the adapted battlecruiser, and the voth bastion as options.
None of those are anything more than marginally more or less useful than the avenger or fleet assault cruiser though. At least as far as the a2b build goes.
Well, I switched to A2B on my Tactical Odyssey last week to try the gameplay (never did A2B before). I'm playing an Engineer btw.
With the moderate items on it and the faw-non-crit-bug at the moment and despite I had a hard time to get used to the new gameplay, I was measured to do 7000 dps (Infected Elite).
With better equip, the bug removed and better timing in activating the skills, maybe there is another 1k or more dps possible.
Sure, there are better A2B-able boats out there, but the Tac Ody is fine and effective as well - my opinion.
Obviously, you can use Aux2bat on any ship with two Lt Engineering stations. I've used it on most of the fedcruisers with good success. I'd say the best ship right now for it though is the Fleet Avenger. The five forward weapon hard points allow for higher damage while your maneuvering into optimal firing position with beams arrays and it also has the maneuverability to go with a dual heavy cannon build making it very flexible in that regard. Honorable mention to the Fleet Assault Cruiser, same bridge officer layout as the Avenger, but less maneuverable and lacks the ability to load cannons. Also, the Fleet Advanced Heavy Cruiser works well and can add a little more survivability with that Ensign Engineering station.