Other: the other main things I look for in a HP site, or any other forum,are:

The staff.[mods and admins]
On some sites the admins and mods can be nazi-like in the way they do their jobs. And that makes for a really bad atmosphere.

The users. SS has a really diverse population of users. And everyone gets on, because they have enough respect for each other. It's really nice to be part of.

The forum. How a forum looks, and how easy it is to navigate are important too. If I can't navigate a site easily, I tend to loose interest, and find a better alternative.

Just my thoughts