Personally I'd never choose automatic over stick if the choice is there. I have a 7.3l powerstroke with a zf6 in my f250 pickup. The clutch is pretty stiff, but it grabs well even when towing horses, boats, etc. The low gear in 4x4 low will damn near rip a house off its foundation.
If you can put up with the hassle (second nature to me now) of driving a stick, there are so many benefits:
Longevity - treat her well and you'll get way more life out of a manual. Auto trannys rely on belts/bands which create a lot of heat and friction, just a matter of time til something gives.
Service - manual trannys are easier to work on, lots of full time mechanics wont touch the inside of an auto tranny, they send them out, which tells you something
Control - being able to control shift points and clutch release rate is great for towing or driving in the snow/down steep grades. If an automatic decides to shift on you harshly at the wrong time in the snow it can initiate a spin. I also just feel more connected to the road when driving a manual.
Get you home factor - even with a broken manual tranny, theres a good chance you can still limp it home, also allows the option of pop starting it if you find yourself with a dead battery(s)
Unless you are talking about something under warranty, I'd get a stick. Biggest favor you can do for yourself if you buy an auto tho is install an external tranny cooler and a tranny temp gauge. Make sure to check your transmission fluid regularly both for level and odor, heat equals death to these things.
http://www.skoolie.net/forums/showthread.php?t=9883 - 7.3L 4x4 Shuttle Bus Toyhauler conversion