Structurally things haven't changed much, but it's not that long ago that it got a new theme (the current one, prior to that it was the stock PunBB theme). Two years?
I actually prefer PunBB, but a large part of that is likely to be that I was relatively new online when phpBB was in its prime, and PunBB feels a lot like a cleaner phpBB. It looks and works like the first web forums I got used to, so it feels natural. Functionality wise I get by with Discourse, but as a user I don't see major things I really like that PunBB doesn't cover. A regular mention is PMs, but a PM-less forum has its own advantages - no reason to discuss problems and solutions where Google can't read them, and getting messages somewhat related to a random post from several years ago just isn't productive.
Visually Discourse leaves a lot to be desired for me. In particular I have serious issues telling posts and quotes apart, where a quote a lot of the time can look like the start of a new post and vice versa. I'm not familiar with Discourse theming, but I might look into that at some point to improve contrast, especially if it ends up being the preferred forum.
Note that my comment is purely an answer to "which software do I prefer", not which content base I wish to move forward with. From my perspective it never seemed like the OpenWrt forum got attention similar to what the LEDE forum has received, so comparing them based on content organization, moderation and cleanup isn't reasonable, or important. Maybe Discourse has better administration tools, which is a worthwhile point to bring up for those who can provide input.