The perfect rear axle is going to be based on your needs. It's no surprise to discover that each of these trucks serve different uses. Some need taller gears for highway cruising, some want shorter gears for hauling, towing, and acceleration.
In addition where you live can dictate gearing. For example, someone with an original 1/2 ton engine (216 or 228) that lives in non-flat areas may find a 3:55 gear set sluggish.