Can Thermomix(-style) appliances knead dough well?
German article about different kneading appliances: https://www.ploetzblog.de/2015/05/13/von-klebern-krume-und-knetern-sechs-knetmaschinen-im-praxistest/

In short: Thermomix is okay but leads to a warmer dough than others because of the motor being placed right below the bowl.

Others knead from above, so the dough stays cooler. Cooler dough means more time to proof, means more taste in your bread.

If you want your appliance mainly for kneading, there are better alternatives. He recommends the Kenwood Major or Kenwood Cooking Chef. The Cooking Chef has the advantage of a heating element (like the Thermomix), which is useful for special baking stuff like a "Malzstück" (malt-piece?, introduces a malty taste and needs cooking for longer time on a precise temperature).