I would have to say, hands down, my Cuisinart Food Processor. It's a 14-cupper, does 7 cups of flour (translation 2 large loaves) at one time.
Over the years, it has always performed for me. For many years I used it all day, every day in my catering business. I have 4 workbowls and 3 lids so I was always able to keep it running with minimum cleaning, and it has never, in more than 20 years (yeah, you read right!) let me down. My lids have the wide feed tube, which first came in in 84, and I don't think Kitchen Aids so-called equivalent to it is even close in comparison efficiency.
Everything else in my kitchen is way back somewhere in second place.
Wine is the food that completes the meal.