Well now youve opened a can of worms!!
This is always a controversial topic but I will give my opinion:
Cardinals, not neons (cant stand the heat)
Rummy nose tetra
Glowlight Tetra
Whiptail Catfish
Rams (poor quality ones may bring disease tho and you want to avoid hassle of treating a Discus tank!)
a few corydoras species, not a lot can can handle temp.
Some apisotgramma and dicrossus species, gibbiceps, bitaeniata, nijsseni
Harlequins
Pencil Fish
Ken