How about some small rainbowfish?
Rainbowfish are far too active for a 10g. I think 29g would be minimum for dwarf neon rainbows (praecox)
In a 30 gallon I have a large male blue gourami in with about a dozen tiger barbs. He was in the tank first for about 2 months and then I added the tiger barbs about 4 at a time. They do not bother him at all
They probably don't bother the gourami because there are a dozen barbs in there. In bigger groups they focus more on themselves and the aggression is spread out in the group, so they are most likely to leave other fish alone. But in a 10g, you can't have 12 tiger barbs...or any IMO. They are too active.
The only cories I'd put in a 10g are pygmy or habrosus cories, because they are the smallest at ~1 inch. They don't stay on the bottom, so the only fish I'd put with them would be a betta or dwarf gourami in a 10g.
A 10g is really small so it limits your stocking choices. I have a male betta and harlequin rasboras in my 10g and it works well. The betta doesn't bother the rasboras and if he were to chase after them, they are fast enough to get away. The tank looks kind of empty, but you don't want to overstock small tanks. The water isn't as stable so it doesn't take much to have some ammonia or nitrites show up.
I'd stay away from any tetras or rasboras that get over 2 inches...they are just too big for a 10g.
Loaches are too big for a 10g...a 20g would be minimum for kuhlis.
Danios are nippy, so I wouldn't keep them with a betta. They are also really active, so IMO a 20 long tank is minimum.
I'd go with a few mollies or platies
or or a betta/gourami and some small tetras/rasboras
or a betta/gourami and 6-8 pygmy or habrosus cories
or a colony of small shell dwelling cichlids like Multies or Brevis.
You would have alot more options with a 20g long tank. A 20g high is only better if you have some top dwelling fish. It is just as long as a 10g, so you don't have any more surface area. Since fish swim horizontally, a 20 long is a better option and gives you more stocking possiblilties.