Chest freezers aren't too bad. Most come with sliding baskets to help organize things. As long as you don't completely fill them up, organization and finding things inside shouldn't be an issue. Put pizzas and frozen chickens and your huge sacks of tator-tots on the bottom, and your smaller bags of peas and cans of orange juice in the baskets.
Manual-defrost freezers are more mechanically simple, so they should last a little longer. No fans or defrost stuff to break. Of course, having to manually defrost the things once per year isn't for everyone. I can understand it being worth it to get one with auto-defrost, even if they are slightly less efficient and might not last as long.
As for the defrost, I live in MN and have a screened in porch. Every year I wait for a night that's forecasted to be below zero, and then I unload all of the stuff into the porch and unplug the freezer for the night. It is kind of a pain, but it's a good excuse to wipe everything down inside and reorganize stuff when I load it back up the next day.