There's no magic forum you can build and have it be popular. You'd need either a forum about something, however chances are whatever you think of will be saturated with forums already (Bitcoin for example) or something brand new that no ones done, but it won't be long before someone else does.
No plugin will make your site amazing. running forums is an uphill struggle. Someone will piss you off, you'll ban them, someone else will cry about user X being banned, rinse and repeat. Starting out as a new forum now is tough. Unless you've already got a large number of members and transferring to nodebb (even then, people hate change, and you'll no doubt get the token "developer" who preaches that anything that isn't built in php is rubbish). But again, you can't please everyone.
