Power/performance for 2015+ Expy looks far better for towing. Ecoboost is just a fantastic beast and compares very well to GM's 6.2L. Longevity and durability is a concern, and 4 models old is not much in SUV application. Ecoboost has been around since 2011 in F-150 though and there are a number of 200k+ mile examples for sale.
GM has owned the full sized SUV market forever. Still have 2/3's of the market in 2018. They just work. May not be the fastest, not the best for certain needs, but they work well and a very long time.
Our 2011 Suburban has had very few problems. We have 111k miles in 6 years. It has served as our main family vehicle for 5 of them. It has been very cheap to own and operate excepting fuel which was budgeted. I plan to keep it for another 6 years at least.
Tow ratings can be ignored for this comparison for RVing. Receiver limit is highest on the GM which is exceeded at 8k loaded TT. Payloads are similar. Wheelbases are similar. Pick the one that speaks more clearly from a test drive.
