I would go with the Kenmore first, no matter what others may say, I know it's a D&M design, but it is a true 2 level wash system that the Kitchenaid is not (1 wash arm on the bottom). You will be able to load more in the Kenmore than the Kitchenaid and it will come clean. I have the KitchenAid as a backup machine and do use it, but loading it can be a pain as all pots have to go in the top rack and it doesn't do a good job with them(the Soak Cycle is a joke and a waste of time), otherwise you lose the area in the top rack if you block the spray from the bottom. The Kenmore may not be built like a tank, but I think it will be fine. Sears sold a boat load of those machines.
Doug