Imho, you simply get more performance or better quality for your money with a good architect. If you are disciplined and don’t want major changes during execution, the estimate will more or less fit. But 10% over is probably always possible, just think of surprises with the earthworks. For me, the difference in individual and of course also professional planning alone is decisive in favor of a good architect. The general contractor basically doesn’t care whether the house is properly positioned or if it also works well in everyday life. He will build any crap as long as the client is satisfied with it. They might have a few good finished designs, but these get worse with every change. The architect plans with much more passion. Ideally, he wants to deliver top quality and plan a reference project to showcase his skills. He also thinks about practical workflows inside and around the house and deals intensively with the environment / location / development plan. If you contribute your own work, you are also much better off with the architect. Liability / warranty issues as with the general contractor are less problematic, and scheduling is also more flexible. If the architect seems good to you and is likeable, take him, your feeling about the general contractor is not wrong. The surcharges are a joke; for €2300 I can already get a nice front door and that is supposed to be just the surcharge for a different color. For me, the further spread of building with a general contractor can only be explained by people’s need for security here. And in the end, 90% still pay extra, many even significantly more than they thought at signing.