As a kid I was heavily impressioned by the alternate timeline Enterprise D

It was able to break the Warp 10 barriar and equiped with a cloaking device.
I always thought it looked awesome. Even more than it actually does. (I saw it when I was maybe 10, and had not seen it again until less than a year ago... surprised to see it actually played a smaller part than I remembered)
Other than that, I think I like Ferengi ships. They seem the most realistic.
I have a soft spot for 24th century Klingon ships, the command ships in particular, mostly because I built a model of one as a kid. Romulan ships confuse me. Their structure doesn't make any sense to me. I thought Dominion ships (DS9) look pretty awesome too.