I have the America's Test Kitchen book for 2007, where they reviewed 12 mixers, but they reviewed it more for durability, so they kneaded dough.
The KitchenAid Artisan is Recommended with Reservations - the kneading of dough caused audible strain on the motor, and narrow bowl mouth hindered tidy addition of ingredients.
The KitchenAid Classic (4.5 quarts) is Not Recommended - "KitchenAid's smallest model seemed more like a toy and wasn't cut out for kneading dough."
They recommend if all you are going to do is beat egg whites and stir cake mix, get a hand mixer, which I agree. I don't have the biggest kitchen, so my mixer doesn't sit on the counter. I can't even get to it easily because I don't have the cabinet space to easily put it away. But I still love it. And it's such a pretty blue.