I was thinking of gouramis...which everyone has but nobody's commented on. So I'm thinking I could be right....in the fish store, the gourami's just sit there looking bored. Do they do that all the time?
I don't find any fish boring, unless you never see them!
The fish I find the most interesting are Clown Loaches because they are so playful. They need to be in groups of at least 5 to see their true nature. Cories are quite playful too.
I find rainbows (all types) very interesting the way they "display" for each other with amazing bright colors they can turn on and off instantaneously.