I'll soon be upgrading my 10 gallon betta tank to a 20 gallon long tank. He's perfectly fine in his 10 gallon tank but I am going to do something different with the 10 gallon tank. What would be some suitable tankmates for him?

I've googled this and have found that shrimp, snails, ADF's, and white cloud minnows would be fine, but am looking for some other suggestions if any. I've always wanted dwarf rasboras (like chilis), but wasn't sure. Thank you very much.