Bettas and gouramis for the personality. They really seem to think about things, are curious, have definite personalities. I love the way they wander around the tank, checking things out, and putting their noses in all the other fishes' business.
I love my dwarf neon rainbowfish just for how pretty they are when they school. The bright blue iridescence and scarlet fins. Their shape is so pretty, and they are so thin it is like they are paper when they turn sideways. Together in a group they are just so beautiful.
I loved having horseface loaches but had to give them away because they grow too big for my 55 gal. But those long horse faces are absolutely adorable, and I love the way they burrow in the sand and lounge around with only their heads sticking out. They are very social, too, and would coil around each other as they moved around the aquarium.
Corycats are wonderful, like little packs of dogs running all over the tank.