The V10 is awesome and highly recommended if you can find one. Ours has 4.10 gears and is rated to tow 12,500 lbs.
If payload capacity is important to you, I would not rely on the sticker amount and would run it through a scale somewhere to check it. The payload capacity on our '09 F250 is less than what the sticker or Ford website says by about 700 lbs.
Depending on mileage, you might want to check the front end out carefully. I've read that the front end on these is notoriously weak. I rebuilt the entire front end on ours when I first got it despite having only about 100K miles on it. The shocks were totally shot but I was planning on installing Bilsteins anyway.
I wish ours didn't have 4WD because we have no need for it. It's higher off the ground and takes away payload capacity. If I were to buy new, I'd get 2WD.