The 4.0 ranger is a great truck, and with elect trailer brakes and do what you need. But if you can swing it the 150 is the way to go, room to grow and it weighs more so more control and safety while towing.
I had a 4.0 ranger that was a great tow truck. Towed better than the wifes 1500 Z71 with the V8. Both were 1998's. Sold it years ago, but still miss that little truck sometimes :-)