Welcome to TPT!
A 90gal tank is nice, lots of room to play with- especially if you want to stock with small fish.
Most tetras would work in a 90gal tank. I prefer to have large schools of just a few species. My personal favorites are Cardinal tetras, that's what I'm re-stocking my own 90gal with. Along with plecos, cories, and amano shrimp.
Many species of dwarf cichlids would also be appropriate (angels, rams, apistos, keyholes, kribs...)
I'd pick one fish that you really are drawn to, and then you can plan the rest of your stocking around that, to make sure all the species are compatible.