I switched to rbenv over rvm and I actually find it really intuitive.
Kinda as a personal manual, here is a list of the most used commands.

Install rbenv

Use brew as the default package manager in osx.

brew install rbenv rbenv-build

Append the following code to bash or zsh profile to initialize the rbenv command.

echo 'eval "$(rbenv init -)"' >> ~/.zshrc
source ~/.zshrc


Fetch the list of available ruby versions

rbenv install -l

Install the desired version

rbenv install 2.3.0

Make it available globally

rbenv global 2.3.0

Or make it local. Each directory can have a local default ruby version.

rbenv local 2.2.0