What's your favourite forum software? For free I have to say SMF, or Simple Machines Forum is a stable choice, also MyBB and phpBB aren't bad. If you're willing to pay then certainly xenForo all the way.
I'm MyBB when it comes to a free forum software all day. If I felt like throwing some money out there I'd used to have preferred IPB but Xenforo seems to have been growing pretty well and it's a better deal it seems.
I'm not sure why all the love for Xenforo. Is it because it's the cheapest one out there? Sure it's good but I think IPB is way better. A better platform, better customization, better spam control and better customer service.
For a premium software I would say that Xenforo is definitely the best for me. As a free option I would choose MyBB. Both of them are very customizable, very user friendly and have a lot of features.
I like this forum software now. Earlier when I was using my tablet, the layout was bad but now everything works. I don't really use many forums and I don't know other forum software to compare.
I like both Xenforo and SMF, although I've only used Xenforo, I like it's looks and additional functionality, but as a forum administrator, I'm familiar with SMF, and because I'm a cheap... person, it's free.
For free software SMF is my favorite! I'm slowly starting to warm up to modern forum software though like Discourse and I've been trying Flarum lately. As for paid software my favorite is Woltlab Suite.