While I do personally prefer Woltlab as I've been using it for over a month now, it is easier to find plugins on Xenforo than on Woltlab. However, Woltlab also comes with a CMS whenever you purchase a forum license free of charge. So if you're wanting to create a blog and a community all in one, Woltlab is the better solution. I even think the theme editor is much easier to use than Xenforo's, and it shows you in real time what you need to edit on a theme to get the result you want.
I’d pay a little bit more and go with XenForo. I’ve actually got a free license if WoltLab that I’ve never used. I like the look and feel of XenForo much better.