Nothing wrong with 10 gallons.
Here are some ideas, if I were going to stock them as display tanks (not breeding tanks).
8-10 ember tetras
6 Yunannilus cruciatus loaches or rosy loaches
3 sparkling gourami
6 pygmy cory
15-20 phoenix rasbora or mosquito rasbora
10 Neocaridina shrimp (RCS, snowball, yellow, or blue pearl, etc.)- you'll have more shrimp in no time, cover the intake of the HOB.
A few CPO's (Mexican dwarf crayfish)
Or, if you want to try breeding, you could get a nice strain of fancy guppies or endlers, and pack the tank full of hornwort (gups will eat fry, endlers won't). You will have babies in no time and if your strains are nice enough, you may be able to sell to your LFS or something.