I was not aware that the RST trim came with the Premier. The Tahoe might not come with the upgraded dash as the Denali trim level does and with that the HUD. Based on your info though it comes down to personal preference. The trucks are basically a wash as they are the same. Personally when I was looking, I drove both the Yukon XL with the Denali trim level and the Suburban with the Premier trim, now the sub did not have the option then of the .9 liter bigger engine and the 4 extra cogs but I chose the sub because I did not like the frontend of gmc, it looks too smashed into a wall look as well as the jugear taillights that look too much like a Ford. Again just a personal opinion