I ordered a Denali a few months ago... still waiting for it to be delivered (it was built March 4th). Most people on this forum would go with the AT4 which makes sense. I agree that it looks better and has more off road capability than the Denali. For me, there were a few things that made decide to go with the Denali at the time, but I would definitely reconsider now. First, I will never go off roading. It isn't something I have any desire to do, and isn't in my line of work. Maybe a dirt/gravel road here or there, but nothing that requires a lift. My truck is used for mostly woodworking and landscaping work around the house, commuting in poor upstate NY weather, and some family road trips. The adaptive ride control makes more sense to me from a comfort standpoint.
Secondly, the lift/height make things a little more difficult for my family. My wife is on the shorter side, and I've got a 4 year old son. Easier ingress/egress is important to them (I personally don't care). Additionally, the height would make things a bit tricky if I am doing work on it in my garage.
Third, I get GM Employee pricing. When I ordered, the AT4s were actually slightly more expensive as the employee discount wasn't very high. The AT4 is a more desired trim, and I think inventory was low, so they didn't have a big discount on it. That has changed, and they now have the same discount as Denali's. If the discount were the same, I probably would have reconsidered. A similar spec AT4 is actually about $4000 less than the Denali I ordered- and what do I get for that $4000? Nicer leather, power steps, 22" wheels, and adaptive ride control? I wouldn't consider that a great value. And that is why most people should go for the AT4.