The problem with a Sierra denali is now buying which of the two engines you think is less likely to self-destruct early on.
GM is already in "customer satisfaction campaign" mode for the 6.2 v8, AKA voluntarily replacing engines, due to a very high premature failure rate (likely attempting to avoid the all-but-guaranteed class action they were going to face). They're in damage control mode because the 8 speed transmission class action just got approved on the 2014-2019, and the lawyers have already filed a secondary lawsuit to include the 2020-2023 transmissions as well (which will likely get approved, as its the same design as the previous yaers). The 3.0 diesel isnt stellar at this point either..and not ideal for those who take short trips...and you'd be doing yourself a dis-service to buy denali trim and willingly take the dog 5.3 v8, which is known to be more problematic than both of the other two engines, combined.
Thats not to mention leaking roofs, known problems with the new infotainment system (software upgrades frying headlights), losing sound entirely...and known problems with the new tailgate latch, with it opening on its own while driving, due to water getting into the new electronic-only controls.
Whatever you choose to spend 70K+ on nowadays, you may be surprised at the quality issues you run into, regardless of brand. Toyota sure as hell isnt a safe bet anymore either.