I've been following the Discourse updates for few month lately and so far it is getting better. It is modern, simple, clean and sleek. Now days communities love simple and sleek appearance (looks at twitter) and the features of conversation are nice.
When it comes out of beta, i am planning on using it and integrating it with our homepage system.
https://meta.discourse.org/
I've suggested to them to add social features with feeds like twitter and our homepage
http://i.imgur.com/12hhUKL.png and they are open to these new ideas and suggestions. So if they were to be implemented, it would definitely be a step forward over VB, Xenforo and IPB since i never see any of the 3 taking a different approach, other than keeping the basic forum functions and features with all their updates. They just don't want to take that next level of social sharing between your friends, followers and the public.
A Discover tab with hashtag # feature and @ feature is a very unique feature that is important and fun for users as well. Everyone likes to share something with his friends and followers and for that shared stuff to be reblogged/retweet, favorites or liked, it always encourages more activity as well.