most of the time, i prefer a manual transmission., but there are instances where an auto is flat out better, so it depends on what you are going to do with the truck, and thats really the bottom line. any sort of rock crawling or 4 wheeling is an ideal situation for an auto.
my mum likes manual transmissions but one of her legs is getting pretty bad, she cant really clutch anymore, so she has to have an auto.
i like a manual transmission for bump starting in a truck, push starting in a car or motorbike, more fuel efficency, more control, less maintence, longer life, cheaper cost, less weight, easier to replace, cheaper to replace etc etc....