I like the Legion.
It's a fun, lumbering Battlestar-style ship that does very well in fleet engagements. Fun to Captain and a good partner for your flagship, when appropriate. It's a
T H I C C B O Y
so you can easily hide most any ship behind it. With mods and Officer skills it can really get the crap kicked out of it, too.
It's not particularly flashy in terms of sustained firepower, and absolutely requires SP on building in mods, but if you're not spending SP on your Capitals, do you even have a pulse?
An added bonus is that Alex hands out several you can find while exploring, so there's really no reason not to field one at some point.
It's just... fun. Not super competitive, but fun.