About 2 years ago, I used Drupal CMS in my first project. When I did my research for a potential platform for that project, Drupal 8 was there. Seeing the limited module support (in Drupal 8), and my own limited familiarity with the Drupal platform as a whole, I made the decision to use the version 7.
The decision paid off! Firstly, there were plenty of well-tried and tested modules to provide almost all needed components of the website. And, secondly, it was much easier to get help from the Drupal Developer/User Communities. In short, Drupal 7 was mature, well-tried and tested, and stable CMS.
Despite Drupal 7's maturity and community strength, though, getting into the Drupal world was not easy. I immediately stumbled on integrating JQuery on Drupal, some already working codes (I was thinking copying and pasting should work) did not work, and Drupal's hook concept was a totally new concept for me. I immediately got the message that "Drupal has its own way of doing things."