Good used mid size SUV for towing

Highest weight rating versus size I've seen is a Dodge Durango. They are a very capable mid-size tow vehicle that get relatively good mpgs and have a nice solid chassis. Most of the vehicles being mentioned I would consider small and the OP asked about mid-sized. A Durango is definitely in a class smaller than a Tahoe or Expedition. I got one once for a rental when my truck was in the shop and was very impressed.