First impressions - OMG. Buts that simply coz I can't read light text on dark backgrounds. Lucilky I found a style chooser at the bottom.
So, ignoring your default style for the above reason.
Style fromBasics Light
1. You haven't removed your guest message from the forumhome template so you have two lots of the welcome message resulting in an ARG:3 UNDEFINDED error in the standard welcome message.
2. Otherwise nice clean style.
Again, the other styles I can't comment on as they are Black/Dark backgrounds.
A nice change to have a dark backgrounded site with a light alternative though. Some sites just have the dark and that is an instant close the browser and go away message for some people.
Finally, if you don't want to have the default style available for users to use then you can deselect that one in the style manager and still select the others which are child styles. Just a little hint there, as some people don't realise that the parent style doesn't have to be visable.