Imo monsters and just something very 'outside the box' adoptables that you don't regularly see? hmmm

I would say try season/nature/plant themes those always make good adoptables for behaviors and what not

Cervine critters seem to be very popular, as far as adoptables ago. Also seconding seasonal/nature themes.

Exotic cats combined with other local animals of that region I that cat

Bird hybrids!

Ferrety type creatures... :3

id say take something unpopular species and mix them in with some common ones~
or just go with the furries you really dont see around fa, like badgers, anteaters, armadillos, elephants, tapir, turtles, bugs, Civets, camels, bandicoots, exotic owls, frogs, salamanders, lizards, monkeys/gorillas porcupines, hedgehogs (not sonics) ferrets, fossas, penguins, platypus, hamsters/guinea pigs, exotic fish, jellyfish, llamas, manta rays, meerkats, moles, opossum, Quoll, ducks/swans/cranes, or you could take bits n peases you like from 3-4 species and make your own race~

anywho, if you take some of the less popular species and give them a bit of your artistic love im sure they'll be amazing ^^

I second this. :)