Backdrop has a built-in upgrade path from Drupal 7. Backdrop is a great alternative for people with Drupal experience because it is so similar to Drupal, and it includes numerous usability improvements and new features.
If your old D7 site is still chugging along, get reborn with Backdrop.
The staff at LCATV found the transition to Backdrop to be fairly smooth and appreciate some of the more user friendly elements that Backdrop brings to the table. Backdrop is very similar to Drupal 7, so it made their lives easy.