I have always been a great admirer of Drupal — since about version 4. Unfortunately,the latest release has become so complicated, I started looking around for something else. I understand why it has become complicated, but it is more than I usually need.
Grav is another alternative. Like Pico, it is a flat file CMS, with no database back end. There are a load of modules available, and it definitely looks promising. This site id in Grav.
On the more complex end of the scale, Silver Stripe also looks good. With Drupal, you can do an awful lot in the web admin pages. Views, Pages, Content types, taxonomies etc can all be configured with forms. Silver Stripe requires you to define things in text files and to write code. It is hard to say which is easier — they both require a lot of knowledge to get things right. Drupal, though, gives you options to select. With Silver Stripe you kneed to know what options are available.