Underrated Mon or Furry characters are indeed something which would be interesting - like characters from some of the 70s/80s cartoons we watched, forgot and remember when we see images from it.

- From games my mind jumped to e.g. the cast from the Saturn "Tempo" games, from Pokémon mostly the BUG type mons, from media characters from Animalympics (which are NOT the Lioness)

Tart from Eto Rangers
Carla from Samurai Pizza Cats
Morgana Macawber from Darkwing Duck

Underrated Pokémon and Digimon

I wouldn't complain to see some Sonic babes like Sally Acorn or Nicole the Lynx

Disney Nessie Art would be cool

Shin Megami Tensei got some nice furry gals not everyone knows about

I'd say Peppy and Slippy from Star Fox barely get any art compared to everyone else. Would love to see rule 63 versions of them in your style

Hmmmm... How about some un popular Pokémons or just one that don't get drawn often.
Some like Mandibuzz, Braviary, Wyrdeer, Reuniclus, Venomoth, Politoed, or Tyranitar

Or something from a show.
Like Lexi Bunny from Loonatics Unleashed

A little late, but...
Crusch Lulu from Overlord :3