Elixir, Erlang, Ruby, Node – asdf.
Java – jenv.
Haven’t tried switching versions of Go and Rust because their updates are 99% of the time of high quality. 
And I prefer to always be on the latest stable version.
OCaml has opam which works very well. I just wish it was less tedious to use, it’s like they are afraid to introduce any convenience and you end up executing 2-4 commands for stuff that should really take one (like have separate environment for every app you are working on; that takes some doing but I’ll hand it to them that it’s possible and works very well!)
