It's a bit small for Tiger Barbs as well, they love to dash about, and are best in a good shoal. Cichlids could be good; you could have two species of South American Dwarfs if they have different spawning requirements, ie one pair of open spawners and one pair or trio of cave spawners. Add a few small tetras or pencilfish, and maybe some Otocinclus on algae patrol.
Cockatoo Dwarf Cichlids are great if you can't (or don't want to) provide soft water, otherwise
Apistogramma agassizi, A. trifasciata, A. borellii etc for cave spawners. For open spawners,
Nannacara anomala are excellent and OK with hard water, also
Laetacara dorsigeros, curviceps etc, or Bolivian Rams. Also normal Rams and Checkerboards for soft water.
The third option of 'Other' is hard to comment on
