well, personally, I'd rather go with the 150. Just all round better. I love my ranger, but sometimes, it just need to be bigger when towing. You never know if something comes up and you need that extra wieght, stopping power, or engine.
I do know that a 4x4 ranger, with 33in mud tires, can win in a tug of war with a FX4 f-150 with the 5.4, off pavement, and on pavement, well.. stalemate everytime.