My favorite would probably be the ranx dreadnought- face it- everyone loves that ship (except when it's chasing after you... than everyone hates it)

I'd probably nominate one of the newest freighters for best-modeled (an Antares class, probably class V... or maybe class I)
As for ugliest... Well, I'm not sure if it really counts, but the OoP's gunship (the short, stubby, round one...) keeps making me think of evil mustaches chasing after me...

The most original would probably be... I dunno... I'll have to think about that.