I'm currently keeping 4 different types: Albinos (c. aeneus), peppered (c. paleatus), pandas (c. panda), and Gold Lasers (c. sp. cf. aeneus).
The albinos are definitely the most active and boisterous. They swim all over the tank, bumping into one another, and other fish! Very fun to watch. I have 7, but they don't really school together too much...
The three other varieties i keep pretty much stick to the bottom. They will swim to the top on occasion.
The Pandas are my second most active bunch, and they school together really well, so it's really neat to watch them patrol the tank. I've got a group of 4 of them.
The Peppered corys only number 3, so they school rarely, but they interact with each other quite a bit. They are also the largest of the corys i'm keeping right now. They are not the most attractive though. I think they're kind of bland-looking.
The Gold lasers are still juvies. I got 4 of them at a club meeting auction. They are very, very cool looking. They're fairly active, but still pretty shy. I'm looking forward to seeing them develop. I really wish i had more of them. The breeder said he would contact me when he gets another successful spawn.
So....
I'd have to say i like the pandas the most. Fun to watch. They school well. Attractive, and not too big.