Gday Paul
I have a V8 auto, and it depends on what you are towing and where. On the highway, the auto is brilliant, much smoother, but if its over 35c, autos overheat more often than manuals as you have the auto gearbox dumping its heat into the radiator as well. Around town I might lean towards a manual more with the stop start slippage heating up the box. (somome once said that for every 20 degrees above standard you halve the life of your auto box)
Off road with a trailer is a lot smoother than a manual in normal going, and when low range is selected I can select the manual swith on the console and lock it into a gear and get engine braking too. Hill Descent is a little quick with a trailer on so I would prefer a manual for descending with something behind you pushing you down the hill faster than your would like!