I have a 2021 GMC Sierra AT4 with a 3.0 Duramax. Bought it with 6,000 miles and now have about 43,000 on it. We love it. It rides nice, gets great fuel mileage and has plenty of power to pull/haul whatever I need it for. It has 20" wheels with Bridgstone Dueller A/T tires. Great tires. Recently had recalls for transmition shift module programming. The dealer took care of it. 1/2 hr. each time.
The one down side is, that I hate the mirrors. They are too small and DS has the convex in the top left corner. Hate that. PS mirror has " Objects appear closer " mirror. Hate that. Can,t back up a trailer and judge distance. I have looked into changing them with a OEM tow mirror but because I don't have the correct option in the BCM the dealer says that it can't be done.