There's nothing really you can do, it's just that many people that I talk to on forums usually prefer vBulliten, including people on forums NOT powered by vBulliten.
If you're not changing the format then I suggest you lock this thread.
Trust us guys, we have considered using vB in the past, but the decision was made a while back to stick with MyBB for various reasons. Money was not the issue, as the monthly server costs are more than a lifetime vB license (edit: $300 now? That's alot more than it used to be), not to mention the advertising we spent early on and the prizes we gave away on launch day (which together exceeded $3k).
With our current skin, we kinda sacrificed functionality for cleanliness. With the feedback we received after the release of this skin, we started work immediately on a different one (as opposed to further developing this one) to rectify the shortcomings of this (very clean) theme.
I'll also point out that when we first enabled the green advertisements, they were very few in number and did not cause the errors we are now seeing. We are working to rectify this.
The next theme will feel more "familiar" and easy to navigate, as we are designing it with this in mind.
What the hell, MyBB is a free forum generator. Anyway, yes, vBulletin cost $300 USD for 12 months. I'm glad you're redesigning the site. 
Actually, I would prefer we use this thread to show what features our members are looking for that can be found in vB.
The reason people prefer vB is because most (large) forums are vB, and most forums that use anything else do not invest much time into developing it, coding new features, and installing plugins. If we felt like we were limited with what we could do in MyBB, we would gladly switch to vB. Though vB did present some advantages, we felt like MyBB was the superior forum system and decided to stick with it.
What the hell, MyBB is a free forum generator. Anyway, yes, vBulletin cost $300 USD for 12 months. I'm glad you're redesigning the site.
MyBB is free, sure, but the server that MyBB is installed on costs money.
Feel free to make this a sticky and a Site Format Suggestion thread.
Even tho the forum system is free, they still need a server to handle traffic and bandwith.
Locked.
A new thread will be up to accomplish that task so that we can start over with a clean slate and so that everyone is clear about the thread's subject.