Majority of our projects are still done in Drupal 7, simply because of stability and the number of available modules. Even though everyone in Drupal community is talking only about Drupal 8, it will definitely need even more time to catch up.
Meanwhile, it's finally time for me to seriously start picking up Drupal 8. This will be the fourth time: I started working with D5, shortly after moved to D6 and finally D7, with which I spent the most time. So far, the biggest change was D6 -> D7, but that is still nowhere near the number of changes D8 brings.