What I particularly like is an open design, without ceilings, so the room goes all the way up to the roof. That looks so cool... That's why I came across EBK-Haus. Their homepage also reads well, you quickly find a lot of information (just no prices). The company is not based in southern Germany, but according to the homepage they also build abroad, so they are probably active nationwide and will also be able to build a house in BW. Maybe there are also other providers who have the open design in their program?