There are so many CMS systems on the market. Hard to choose one. Just to mention it at the very beginning: I am no professional Web Designer therefore I don't look at the heavy weight professional systems at the market that have a harder learning curve. So you may disagree to my decisions but I want to share my requirements and thoughts with you:
Security is important
You don't want your side to be hacked and content will be changed without you knowledge. Even worse malicious code could be injected and you are in trouble.
So watch out what systems had known vulnaribilities in the past and how fast were those fixed. In my opinion popular systems with a lot of 3rd party plugins are propably easy to handle you get a lot of stuff but on the other hand the risk of being affacted by a security problem is high. So even I played around with Joomla and Wordpress they didn't suit to me.
Easy installing updates
As a good compromise I used Typolight and successor Contao for a while. It's ok, not too hard to use. It was not my favorite CMS system regarding its user interface but it did the job.
Why I decided to go away from Contao was the problem keeping the system up to date. And a reason behind this is need of a database. I bought professional themes i.e. from Rock Solid Themes. I cannot complain - they have lifetime support for your theme what means you get new versions of the theme needed when upgrading Contao to a new version. But the combination of upgrading a theme and then upgrading Contao - running the upgrade tasks from version a to b - then from b to c and so on until you reach your final version failed so many times on the way that the page became unusable too often.
Stabilty over the years
Consider you don't change anything at your CMS system. You expect that it will run over years. But this assumption is wrong if you host at a "normal" web hoster. The hoster will update his operation system regulary and will patch this and that. This means for example sometimes he is forced to update the php version. And this could break your cms tool unless you update it to be compatible again.
Having a copy for staging
This means - away from the editorial process you may want to have an exact copy of the system at a different location. This was a hard job as well. If you install a system at your hoster they did a great job in the background to provide a database, php environment and so on. If you want to copy your page and want it at home - setting up database with correct collation and php with all needed components could be a job for a couple of hours. And yes if this would be always straight forward - I wouldn't complain, but too often I faced problems that the database default size of system stuff bite me.
At this point I was wondering - why do I need a database at all? Copying just the files from hoster to a prepared virtual machine could be so much easier and more robust.
After all this, I searched for a flat file CMS
I found grav. This is the system you are currently reading at. I am just at the beginning using grav. But with the background of a developer, I can say that suits to me. I like the user interface - it's straight forward. And the best - if I don't find the right button, I can just edit, copy, delete files at operating system level and I am done.