Anyone who buys an brand new car is a complete sucker and Scotty as talked at length about it.... If your going to buy one buy a 2016-2017 at most because you have some history on the cars in general and you're not gambling on a brand new car. AS far as what engine.. It depends either should be fine but are you going to be towing or hauling big things? Then get the bigger engine? Are you never going to tow anything get the smaller engine. Just whatever you do don't buy a brand new car. You lose THOUSANDS of dollars the second you drive it 1 mile. Since you in the market for a new car check Autotempest.com for the best used cars to find the best price for what your looking for!

I have heard anecdotal accounts that the 5.3 has recently been experiencing many more failures than older ones.  Not sure how the 6.2 is doing.

Are you willing to pay the fuel difference for the 6.2? 

The 5.3 is going to be the choice of the vast majority of owners, so if you need parts....and you will....they will be easier to find.

I would advise you against buying that extremely overpriced GM, but you seem set on it and hey, it's your money. Just go ahead now and make sure you are willing to spend some time in a dealer loaner car while it is being worked on because I'm telling you, as a former GM employee, it will absolutely have issues.