Discus are good, but require a lot of maintenance and patience. Another one would be some geophagus like balzanis. Be carfeul though and do your research because some geophagus get large and aggressive while others stay small and timid.
Keyholes are your best bet. Non agressive, stay small (10cm max), hardyer than most things and very cute looking.
Other than them then Kribs or Bolivians are worth a look. I presume this is a community for small (5cm) fish.