Ooooo soo many options or a 55g community. They are really fun to stock
If you wanted to go the smaller schooling community fish route I would be hesitant about adding angel fish. I've seen some angels that were pure sweet hearts and wouldn't hurt a fly and then you see some of them that are nothing but bastard coated bastards with bastard filling and love to harass everything in sight. They will also get quite large. If you can find a LFS
that will let you trade them out until you find a nice one then that might be a good route to go.
As for other stocking options I always suggest some harlequin rasboras. Aside from those a bristlenose pleco would work nicely. German Blue Rams are especially nice looking fish and you can fit 4 of them in a tank that size although I seem to have a hard time keeping them alive for some reason because they are really sensitive fish. Zodiac loaches are also really entertaining fish. Really the sky is the limit with freshwater fish in a 55g unless you like the really big species that is.