I have been using vbulletin to build a few forums over the years.
I have had great exceptional success in a couple of them , over 5 million hits per month with 70 plus paid advertisers. I did not pay for traffic just dedicated members.
Rules for success = The forum must be unique. That means loyal users.
Games , chat rooms etc don't help a forum.
You must have constant updated content and the best content is provided by users.
You must have a real easy to remember domain name.
Finally try to have a forum about something that you and others can have a long interesting conversation about and not be boring.
Selfies, social media events are all boring. You are competing with millions of others.
Now if you had a forum on how to make buggy whips that would be unique.
Otis