Well, its totally dependent on the user in question and what it's being used for for example mysite uses a dark theme (runaway) thats solely based on the fact that my small community servers are based around the zombie genre.
For a forum like this a light theme is most suitable as it's more or less a service provider, it's providing us with the tools to run our xenforo forum, the light theme for this forum makes it more processional which im sure the staff agree with.
So in conclusion, it's down to the user and there specific needs.
Thx for your views guys since vote is currently 50/50 , I will gonna wait for some more votes of people to check in which theme people have more intrest , though currently I am just looking for what people think about dark and light styles
You should adjust the design to the specific colors of your community, ligher colors are more common for active community websites and hosting providers, darker colors are making you more tired. It's personal opinion at the end of the day .