I like cardinal and neon tetras; rummy nose tetras are nice too. Zebra danios aren’t colorful but they are active and fun to watch. I also like angelfish, and need to get a pair for my tank:-) (Currently I have danios, neons, and glowlight tetras.) I like the glowlights well enough but I’m not sure I’d get more; when they matured their colors weren’t as bright anymore.
I know a lot of people like clown loaches, and they are attractive, but they get big. This site recommends at least a 75 gallon tank.