Either one, choose the long wheelbase version, Expedition Max or Suburban/Yukon XL.
Both will have the same limitations well under the model's maximum tow rating. When it comes to family RVing, the tow vehicle's payload likely be the first rating exceeded. As you shop take a look at the Tire and Loading sticker of something close to the equipment you want. 1900 pounds listed on web sites ends up being 1400-1500 pounds with popular equipment people buy
Powertrain/Performance: Ford hands down. It has 4 more gears offering tighter ratios and wider overall spread, which leads to less dramatic towing. The engine has significantly more peak power as well as broader torque profile which will keep the engine in the 2000-3000rpm range a lot more often than the naturally aspirated 5.3L. Longevity and exhaust note I'd bet $100 on the GM. Very reliable V8 engine refined over almost 20 years.
Honestly, I'd drive both and let the wife pick.