Wordpress is an option too, there are community mods for it and template can be made from scratch or adapted from whatever free template you decide on - plenty of tutorials out there too, if you are new at it. A bit of plugin coding and you can add whatever type of extra feature fitting a guild that you can think of. Social login plugins adds support by a wide range of social media, so wether people have facebook, google, twitter, etc.etc. they can use it to log into the site. Flexibility is depending on wether or not you host it yourself afaik.