As long as your Betta doesn't mind tank mates, ADFs are great combos with them. I kept two with a betta in my 6 gallon tank for a while with great success. The betta seemed fascinated by the frogs, and the frogs are just goofy
The ghost shrimp might be froggy snack food however. If you go with the frogs make sure you feed them frozen or live brine shrimp/bloodworms (freeze dried causes blockages/bloat, and they won't eat pellets or flakes) via a turkey baster to make sure the betta doesn't pig out on all the food himself.