XenForo seems to be the popular choice at the moment, though IPB may be catching up a bit. Both are a lot more traditional than the likes of Discourse, but they

XenForo seems to be the popular choice at the moment, though IPB may be catching up a bit. Both are a lot more traditional than the likes of Discourse, but they're the scripts many vBulletin owners migrated to when Internet Brands basically killed the company, as well as the ones with the most mods/community support. Not sure about the state of open source forum scripts, though I don't recall phpBB/SMF/MyBB being replaced by anything else in that market recently. But personally, I'd recommend XenForo. It's what most of the sites I run use (see Wario Forums for an example), and it's what many sites I'm a member/volunteer on use too (like The Admin Zone or Gaming Latest). Lots of choices for themes and mods there, it's pretty fully featured as far as basic options are concerned and the media gallery/resource manager work well too. The fact many members weren't too keen on the other solutions I suggested helped too. But yeah, XenForo is my recommendation.