Well, everyone's taste is different and all animals have certain good qualities, but if I had to pick some faves, they would be the following:

Spanish fighting bull Β© David Cordero

King ragworm Β© Alexander Seminov

Rosetail betta Β© aquafisher.org.ua

Mustang Β© D. Robert & Lorri Franz (to be fair, all horses are amazing, I just prefer the fat-looking breeds)

Dragon snake Β© Dean Carguillo

Goliath heron Β© Arno Meintjes
And of course almost any leucistic, albino, erythristic, melanistic, or abundistic animal! Though I don't endorse specifically breeding for these colors variants (at least not in non-domesticated animals), they are very very beautiful. I would add more animals, since they're all so gorgeous, but if you really wanna look at pics of my favorites, I've collected a bunch on my Pinterest :3
https://dk.pinterest.com/hostilepopcorn/me-animalia/