For a small tank, Pygmy cory's would be good, also Celestial pearl danios (galaxy rasbora), threadfin rainbows, maybe copper harlequins, lamp eyes and for sucking type fish, octocinclus. Kuhli loach may also be good. Check adult fish sizes before purchase.
I too have had bad issues with cherry shrimp, all forums blamed the water, but they are prone to bacterial infections and colonies can die out rapidly ( exactly what I had).
Dwarf gourami are prone to a virus in which they waste away and die. I think they must be prone to bacterial issues as well, another which I have had no luck with.
We have a 450 ltr tank, 180 ltr tank, a 19ltr nano tank and a 2 ft quarantine/breeding tank.