Well, a (very) amateur here. I just want to throw a short story about this:
When i (tried) to setup a fansite for Chrono series, my first thought was to make a portuguese version of the major english fansite about the series, and it has three modules: a forum, a front page and a wiki. My (non) brilliant idea was to get PHPBB, Wordpress and MediaWiki. Bet what was the result?
I suffered
a hell trying to simply make the three CMSs look and feel match. And worse: i dont know
NOTHING about OOP on PHP, so i simply cant learn nothing about stylizing MediaWiki.
Was then i learn the fabulous world of the simple modern-looking, flat-file CMS floating around.
First i found
DokuWiki. I really like it! Very simple to manage, comes with a lot of plugins and you can host this on a very shitty free web hosting.
Second, i found
Grav. From what i learn using it (very little, i didnt used in production because the fansite was already structured) its a very good and simple alternative to wordpress.
And then i found
MDWiki. Very simple and raw. Only for those who like to organize themselves the site file structure (this is the reason i like it, plus the markdown parser).
I still searching for a flat-file CMS for forums.
But from the experience i get, if i build another personal website i will definitely went with they, due to simplicity.