I would recommend
Bilstein's...... You will be more than happy.
I have them on the Excursion, and they improved the ride significantly!!!!! I linked to the
Bilstein Website Listing for your truck. The ones listed for your truck are the same model I have on my truck. I know that RLDSL has Bilsteins on the back if his truck, and he has reported only good things on them. They have a lifetime warranty, and stand behind it. He had one he thought was bad, send it in for testing, and I believe they found it to be below their standards, and shipped him a new shock!!!!! They would truly be the last set of shock you have to by for your truck, and more than likely, the last time you will have to change them too!!!! I have seen reports of 100,000+ miles with no performance degradation from the shock.
Shop around, I found the local 4 Wheel Parts (national chain) had them on sale when I needed mine. I was able to order them, have them shipped to my local store and pick them up for less that I could get them on the internet at the time. Just make sure when you order them, from anywhere, to supply the part number off the Bilstein website.... I did not, and the ordered the F-250/350 shock for my truck. The Ex and the F-Series have slightly different shocks. I discovered this, and they ordered the correct ones, and exchanged them no-hassle for me.