Mix'em up!
They can all coexist just fine, it will probably end up depending on what is available. I use both temperate white and tropical pink springtails as well as dwarf white isopods. I use them because they were available. Any combination will work just fine. Check out places that sell dart frog stuff like NE Herp, Black Jungle or Josh's Frogs. They all carry some!

Cheers,
Alex