I don't just mean the posts an thread topics but also the way it dealt with trolls an trouble makers an wether or not admins and mods replied or didn't reply.
Now for me the worst is simply ign I've never been on a sight that's full of so many trolls an egotistical pricks on power trips an that's just the staff let alone the community which 90% are just [censored] and trolls.
The best was Johndouglasmindhunter.com until it decided to scrap it's forums in turn for more article based stuff.