Well, for one, Volta supports Windows! That's a huge differentiator in my book (though as a Windows user I guess I'm biased?).

I have never heard of asdf. When we started using volta (back then notion) more than two years ago, it replaced nvm for us which was just very slow and frustrating.

So not sure what asdf does or how it behaves, but volta is basically a painless "forget that you even have it installed" version of nvm.