I saw another discussion "DISCOURSE IS BETTER" but that's not very productive. Instead let's look at what each does better than the other.

I'm posting this under feature requests because that is where I hope this conversation leads.

Front page. Hands down, it's more fun to browse the magazine style front page. Is it more usable? I don't know but if it keeps time-on-site up and click-throughs high, I don't care if it is less usable if it increases engagement.
Setup. Have you seen or followed the instructions for Discourse? Yikes.
Scalability/Performance. It's not religion, it's just true, Node.js scales better and more easily. Yes, Rails is scalable but it just takes more work and ops time. I want to run my forum not worry about running Rails.
Topic list page. There area similarities between the two but NodeBB leave more space in the side bar for other information about the site. And potentially plugins or ads?
Tags. Last I checked, the Discourse team was vehemently against tags. I like them or at the very least the option to have them.
Ease of theme modification. I actually cannot confirm this but it is supposed to be a core tenet of NodeBB so it wins for at least trying. I did look at Convoe and it looks great!

Email integration. No question here. The Discourse digest is superior. NodeBB doesn't even have email alerts. Discourse even allows you to respond to an email alert and have it post directly to the forum.
Posting a new message/topic. I think Discourse has a slight upper hand here. The help tab in NodeBB is not very helpful. In Discourse, when posting a new topic you can change the category. I think the NodeBB transparent background is distracting.
Title bar. This one might be contentious but I don't understand what or why all of those buttons are at the top. I never touch them.
Ease of reading. Fixed width posts are easier to read. Browser edge to browser edge is not comfortable on the eyes. Period. (I guess you can customize this but I think the default should be fixed/responsive.
Meta-data about posts/links.etc. I think this is very interesting differentiator for Discourse. It's almost like Github issues when you link between different issues. The number of clicks for a link is also really nice.

Search. Discourse search in the toolbar is nifty but I like search results page. The search result page on NodeBB ~~isn't as useful as the results you get from a Discourse search. When I search NodeBB I rarely understand the results.~~ Update: search results on NodeBB are really good now and a slight edge over Discourse because they are on a page and not a dropdown.
Mobile. It's good enough on both.

I haven't explored all areas of both. Any thoughts on

Update 12:10pm PDT: Added customizability to "NodeBB is better"

Community

Dave Jensen