Funny, I went the other way. I just traded in my 2015 Denali Duramax 2500 for a 2020 6.2L AT4.
My needs changed as I sold a business. Before, I needed payload capacity of 2500-3000 LBs. Now that I don't, I did not want to own and out of warranty diesel. Had I not sold my business, I would have traded for a 2020 AT4 2500.
I'll still tow 5-7,000 LBs, and don't expect the 6.2L to be nearly as good. Also, much of towing is downhill, and the diesel exhaust brake has to be one of the greatest components of that platform. I live in Colorado and never needed my brakes going down any of our famous passes with the trailer in tow.
My new job has a lot of stop and go traffic commuting. That is not what a 6.6L Duramax is good for. I have no regrets, and coming from that truck, the 6.2L is a real pleasure off the line. Still, if you need an HD truck, the Duramax is the best platform to go with.