I'm interested in the rarer livebearers- so I suppose that's assorted smaller fish. I have a thing about small fish anyway. The ones I like best in each category always seem to be the smallest: heterandrias from the livebearers, multifasciatus from the cichlids, furcata from rainbow fish, khuulies from the loaches, peacock and desert gobies from the oddballs. The one exception is the cyprinids where I am absolutely in love with the moustached danio.
I just admire the toughness it takes to survive in a hard world when you're the size of a least killifish.