My next car will be some kind of Land Cruiser variant. Likely a 2006-2007 Land Cruiser or Lexus LX470 (both being 100 series Land Cruisers) or a later Lexus GX470 (a 120 series LC "Prado"). If you can afford a nice 200 series (2008 to present) Land Cruiser or Lexus LX570, that would be, in my opinion, your best SUV option. Great blend of towing capacity, off road capability, reliability, and luxury features / overall driving experience. Really the perfect SUV. If you're in the same boat as me and cant afford a 200 series, look for a 100 series Land Cruiser or some kind of GX. The earlier GX460s are really getting to be affordable nowadays. The GX is worth the extra money over the 4Runner on which it's mostly based. Interior is miles ahead of the 4Runner. Not even close.
If you're willing to put up with extra maintenance, there is absolutely no experience on this earth like driving a Range Rover. They are magical (and good tow vehicles).
Denali XL (as they have the bigger engines compared to the Suburbans) and Ford Expedition EcoBoost are great if you really need extra room inside.
All that being said though, no normal SUV can beat a modern full size truck for towing. I don't think any SUV will have the wheelbase of a longer truck and most don't have the power (yeah, yeah, Range Rover Sport.. Porsche Cayenne Turbo.. I know).