I have a KitchenAid, and I have tried all sorts of techniques. For pizza dough, in my experience, it make a decent dough. I much prefer hand made dough. For many breads, it is fine, but, I find that unless I work the dough by hand, I get variable results. I think that there is a flaw in how mixers knead bread doughs. None of the real top notch bakers I know use a machine exclusively.
Since going to an indirect, low temperature rise and higher hydration levels, my doughs have improved in texture and flavor quite a bit, and actual kneading has gone down.