I really like the Defenestrator. It's an obsolete construction droid that entered the the Great Hunt, collected every bounty and wiped out all competition. At the award ceremony a Mandalorian objected to a droid winning, but when he insulted it's honor it kicked him clean out of a 15 story window.
I just think that's a cool backstory for a minor character.
I never liked the Fetts, or that pale chick. I suppose Ventress was a bounty hunter so she's probably technically my fav. Not sure if the Champ counts since he's a PC.