So far, in my opinion, Ruby on Rails is the best web application framework that I have used. Compared to others, it is very complete (by installing extra gems) and mature, provides everything that I need.

Version manager

There are two version managers: rvm and rbenv. I prefer rvm. It allows to work on different projects with different Ruby versions. Node has similar manager, nvm. Python has similar feature, but acts differently, using venv or virtualenv. In Python, we need to install the specific version, and create the environment by specifying our Python version. Contrarily, rvm or nvm will download and build the corresponding version.