Here are some of the reasons that I want to switch over.
1. Wordpress integration. I integrated my vb4 site with wordpress but I couldn't find a modification that would make wordpress articles into threads so that when people comment, it will also show up on the forum. I would probably have to pay someone to do this for me but I've already spent enough time fixing lampwright's wordpress/vbulletin 3 modification just so that it could use avatars from vb4. Don't want to deal with it anymore. I am able to do threads and share avatars with wordpress and xenforo with no problems.
2. Easy Page creation.
Kind of speaks for itself.
3. Easy Navigation of Templates
Oh Goood I hate navigating templates in vb4.
I know Xenforo has a lot of nice features but those 3 alone have impressed me the most. I have spent a huge amount of time in vbulletin 4 Templates and am still disgusted at how laborious it is to navigate at times. This is probably the number one seller for me.
The main reason I decided to try XenForo in the first place is because of vBulletin 4's update version process. Like sh!t will be broken that has no business being broken. Stuff is broke on my site right now after 4.1.4. I'm scared to upgrade anymore. When you create a new style, it doesn't let you. That was a bug they supposedly fixed for 4.1.5 Okay, well... why was that broken in the first place when it was working fine in 4.1.3? You see what I'm saying? That's just one example of some annoying sh!t I can't take anymore.
Then there's this issue about CSS Sprites. I spent a week or two trying to get that working right and it still sucked. No speed or score difference. I'm tired of my vb4 site having a score in the 80s no matter what I do. Added a CDN, added vboptimise, vbsupercharged, optimised images, still get lower 80s score. XF skinning is easy. I am pretty much done. My XF board is in the 90s and I still do not have any CSS Sprite stuff up. I am amazed. A faster site = higher SEO.
Addon's Xenforo's still missing before I can convert my vb4 site over.
Arcade (Coming soon?)
X-Box Live Leaderboards
^^^That's all I'll really be missing. I shouldn't even count the arcade since one is supposedly almost finished. Until then members can play Facebook games on their site with this zynga page: http://www.blackgamer.net/b/pages/zynga/
I did a speed test just now. My vb4 forum home is now getting a 88/100. URLJET upgraded their servers a couple weeks ago so I know it was their doing as I have done nothing to my site recently to increase the score after I gave up diddle-daddling with CSS Sprites.
My new XF forum is getting a 93/100. That's still high enough to warrant me crossing over, absence of add-ons I want be damned. Speed > All. You could say that if I spent more time on my vb4's site that I could get it faster than my xf site but then you would also assume I have the time, money and patience for that which I do not.
I think I'll just wait until 1.1 is here before I switch over.