what are you using the truck for? highway, DD, Rocks, Mud, etc. etc. Do you care about mileage, or being able to crawl up trees.
Id say if fuel mileage is a concern, no higher than 3.73 gears, but with 37's id say 4.10's. If you wanna go crawling, and dont care about fuel mileage, 4.56's or 5.13's.