Here’s a different perspective to your question.
I owned and drove a 2015 Yukon XL Denali for 6 years 149K miles. It was totaled by a drunk driver. Wife was driving her ‘13 Escalade ESV Luxury coming up in 128K miles, she wanted a newer one. Despite me trying to convince her ‘13 is in great shape well maintained and has a lot more miles in it she got a ‘19 Escalade ESV Premium and I started driving the ‘13 Escalade ESV.
Having now been driving the ‘13 Escalade ESV for over a year there are only a couple things I miss about the ‘15.
1. Passive door entry handles. Enables you to unlock and open the doors by simply having the key fob in your pocket. Don’t have to hit the unlock button on the key fob.
2. Push button start.
3. The 6.2L L86 in the K2XX is faster than the GMT900 6.2L L94.
4. The K2XX does get better mpg.
5. Bluetooth wireless audio streaming.
6. There are more USB and car charger ports in the K2XX over the GMT900.
Items 3, 4, and 5 above are fixable with mods if you’re willing to put that work and money into your vehicle.
That being said a lot of what
@91RS mentions above is spot on.
The GMT900 platform definitely rides softer and smoother than the K2XX. It could use a little less sway but again upgraded sway bars solve this and I would recommend them for any model year full size GM SUV owner.
The seats are softer and more comfortable in the GMT900 over the K2XX.
I’ve been running on E85 since I’ve been driving the ‘13 ESV. Something the K2XX 6.2L is not able to do in stock form.
The bi-xenon HID headlights in the ‘13 Escalade are way better than the stock HID headlights in the K2XX Denali. But the K2XX Escalade Headlights are the absolute best. Even better than the ‘21+ Tahoe/Burb and Yukons.
The 6 speed in the GMT900’s is better than the 8 speed in the K2XX’s; Shifts smoother, not as clunky; But the 10 speed in the K2XX’s is leaps and bounds the best transmission available for the GM full size platform.
Just thought I’d throw in my observations and thoughts from a slightly different perspective than what you asked.