Kitchenaid, but the commercial one (K50) not the one which comes in pretty colours. We opted for it on principle (better motor, etc), but a friend who had tried to persuade her DH on Kitchenaids met it this weekend and said that the pretty one's build quality is rubbish compared to ours (so she opted for a Kenwood and is very happy with it)
I have the "pretty one" and I find that the flat beater and whisk don't reach to the bottom of the bowl and I end up with mixture stuck to the bottom. Also it doesn't do anything other than mix/whisk/knead. I think I should have let my head rule my heart and gone with the Kenwood. It does look nice though .
I know what you mean to some extent with a thicker cake mixture but I find giving it 10 seconds on full speed lifts the mixture off the very bottom. I usually stir any recipe with a spatula half way through just to make sure it's incorporated all the bits from the side. I think most mixers don't reach right to the bottom by design.
I binned my ancient food processor at the beginning of the year as it was beginning to smoke a bit (!) and I either use my Kitchenaid or this blender for all my cooking needs now. I'm a sucker for a gadget but I find these two do everything I need.