I had a good experience with grav. It being file based (i.e. no db) made it very easy to understand and modify to do what I needed. The included admin dashboard makes it pretty straightforward to hand content administration to non-dev users
WordPress? Really depends on what website or app you have in mind.
Wordpress allows for a lot of customization, but can get bloated quickly depending on how complex the theme is, and how many plugins you add. I keep my WP install as lightweight as possible.