I know the angel is small right now but they do grow and I found to be quite active fish. I am not saying you cannot have one in there, I just found it to be cruel to watch as this fish would swim back and forth. Reminded me of the Lions in their cages for the circus performances.
I agree with the damsels, they are certainly cute, colorful active fish but they have their place in a huge tank where they can really act out their behaviors....
Another thing you could do is to post a question to see what folks here have in their tanks that are the same size as yours?
Here are some that I would put in but you have to make sure that they are compatible as some you can only have one of, looks like you want to have five fish but make sure they are right for each other.
Bi-Color Blenny
Yellow Clown Goby
Yellow Watchman Goby
Hi-Fin Red Banded Goby
Cardinals
Bi-Color Pseudochromis
Fridmani Pseudochromis
Black Cap Basslet
Royal Gramma Basslet
Cleaner Shrimp(s)
There is lots of color here, keep us posted on what you decide. Is this tank 20 gal??