At KB Brandis and some others you should know that the floor plan should be finished. This means you should either know what you want or have been to the architect.
Not just with some, but in general: this is not a Brandis peculiarity, but fundamentally a draftsman never replaces an architect. That is why BASICALLY (sorry, bold font is no longer possible here) when building with the general contractor, either one of their standard designs should be taken and in it at most a non-load-bearing wall moved, or you should go with your own
architect design. Even "proofreading" a layman's design overwhelms most draftsmen, at least on the creative level (they can just about fix a forgotten masonry connection for a room door). However, a whimsically wished corner window is usually first stopped by the structural engineer.
Otherwise, an acquaintance is building with a regional construction company and is also satisfied. Marco Friedrich Bau from Stendal.
I would also count them among the recommended providers.