Other than the common issues most people face (buffering, vibrations) anything else that you have learned from your 15?
Spending a little more for a newer one would be nice but it would be 5-10k more which is a lot.
... that's basically it. Other than the 10spd tranny, I know some of the tech changed relating to the info screen and entertainment system, interior lighting changed to blue, and I've heard the seat cushions are softer for 17+. There's different things mentioned by some like motor mounts, bushings, reprogramming of suspension, different torque converter, etc. but is probably the norm for any model from year to year.
Our 15 has the buffeting issue but with different tires and having them road forced often has masked it for the most part. We've had oil and tranny leaks, front end needed parts replaced before 50k...upper and lower ball joints. front and rear ring and pinion needed replaced and currently the rear is making noise again. It hasn't been the best truck but I'm willing to give another a try. We are considering the new expedition but leaning towards a burb or yukon xl again assuming I can get a similar deal that we had last month.
good luck