Looked at Tahoe Premier, Yukon SLT and Yukon Denali. I did extensive research. Aside from the trim, grilles, emblems, and basic looks, the Premier almost equals the GMC SLT. The SLT had a more digitized instrument cluster which only comes with the Tahoe Premier if you get heads up display. Otherwise the Tahoe has analog gauges across the top (oil, battery, fuel, temp). The Tahoe Premier has magnetic ride control where the SLT does not. I noticed a difference. Tested them both on the same day. But the options and features are all the same.
So you may be able to get a GMC SLT a little cheaper than the Tahoe Premier similarly equipped. The biggest difference is the addition of magnetic ride control on the Tahoe Premier. The other bells and whistles are the same.
The Denali is a different animal, in my opinion. The main difference is the seats may be a little more comfortable and you get a 6.2L engine and 8-speed transmission versus a 5.3L and 8-speed. If you do a lot of hauling or want to be a speed demon, then get the Denali. Personally, the 5.3L was enough for me and my wife who primarily drives it. If I were hauling, I'd just get a 2500 series. Also, I like the fact that I can put 87 octane in the 5.3L as opposed to 91 or greater in the 6.2L.
Also, I didn't like that it is more difficult to find a Denali with 20" standard wheels. Most of them come equipped with 22" wheels which I absolutely do not like. The ride was very stiff - I felt every bump. I also need a little sidewall to take a truck onto the beach. The Continentals that come with the 20" wheels are bad enough. So because of all of this, I opted for the Tahoe Premier. I liked the magnetic ride control over the GMC SLT and I felt that the Denali was a little too much. I wanted it to have a little bit more of truck functionality. It saved money.
I also just preferred the look of the Chevy Tahoe Premier grille vs the Denali cheese grater.