I’m completely sold on asdf. With the .tool-versions file I can just asdf install in a project and go.
I also love how simple it is to have multiple versions of PostgreSQL running. I use the technique described here to manage the database per project so I know I’m always exactly matching the production version. This has been super helpful when one project is on Heroku and runs 12 or 13 and another is using AWS Aurora that’s more like 9.6 maybe 10.