After reading your post, it's pretty clear that your users just wanted a casino. It has nothing to do with the function of Xenforo or vBulletin.
I know at least a dozen forum owners who moved from vBulletin to Xenforo and not one of them considered moving back. You're not the only one to find that Xenforo's SEO appears to be far better streamlined (no secret) and overall performance is much faster.
My advice is that anyone who puts up a forum should think about what is most important to them. If basic forum activity is most important as well as performance, I find Xenforo is the better tool and opinions might vary. If there are VB specific items like a Casino or some of the remaining supported mods that are important to your users, then there is no reason to switch away from vBulletin. Pretty simple really.