Successful Forum?

I want to get a few members' opinions on here.
What makes a successful forum, in your honest opinion?
What do you love seeing on a forum? What do you hate seeing on a forum?
What aspects do you look for in a forum?

Just wanted to gather some opinions up.

When I first look at a forum, I look to see what makes it different from the forums I'm already on.
+ I don't like joining forums with not content in it :s

Activity - we all know this is one of the most important pieces in having a successful forum

Team - obviously there needs to be a team that is capable of running the forum and keeping it smooth.

Posts - Say if I was to make a thread asking a question, how many replies would I get? The more replies I get the more likely I am to return to that forum to make another thread again.

There are a lot more aspects that make a successful forum but those right there I believe are the key ones. Just turn them flip em around for the bad things. E.g - no activity doesn't make a successful forum obviously.

You need to gather users before starting the forum.
Want to know why?
That way you will get content quicker.