You are in a good position as you can choose what works best for you and there are several trucks that will work. Take your time and find the right truck. Find one where the owner has taken good care of it. I sold my '99 F150 which was a great truck and in great condition at a pretty low price. It had served me well and I figured why not cut the next guy a good deal.
Like Grit Dog mentioned you might consider looking at 3/4 tons just to widen your selection. You will pay more for your gas bill, but you may find a truck in really nice condition. Also, the 3/4 ton trucks are built heavier and may hold up better for you when you are getting a rig with some miles on it.
Good luck to you,
Stu
