What is your favorite free software?
I have always been a big fan of phpBB. It's a very light and user-friendly software, and the level of customizability has always appealed to me.
MyBB is clean and neat. Even after years 1.8 still looks clean.
phpBB has a lot of modern features, but they can do well with a clean theme. I was told v4.0 will have one.
I have always been a fan of ProBoards hosted forums. I started with them back in my pre-teen years and have continued to use them, design for them etc., well into adulthood. They're a little old school and behind on the times, but they are catching up making things more responsive and easier to design for.
I've only had Proboards but I think they are quite user-friendly. You don't need knowledge of coding to be able to do the majority of things. I don't have bells & whistles on my forum, now that you would need some expertise.