If you want to go schemaless, with native key/value pair and JSON support go for PostgreSQL. Version 9.4 is faster than MongoDB for both inserting and querying JSON data.
Why would you use a database for a simple CMS when flat-file databases and web-side caching exist..?
simple ? i would go for sqlite or xml :) both of them don't really need a service to run only a lib and if it's about reads sqlite is perfect for that.
It dependes, but if it's all about posts/tags/categories/user it's better mongo, but if you have a lot of relations and then better go for mysql.
Eitherway it's interesting for search engine to use something like elastic search.
TJ
Building Sparkle ✨ for Laravel | Echo Labs | Curology
Something simple? SQLite, something simple but robust, MariaDB