First of all, thanks again all around – especially from the "passive readers," it would be nice if some would become active in giving their two cents – now, as promised, I want to respond to some suggestions already:
I find HomeByMe better only for interior design (including decoration etc.).
clear 2D representation, integration of building services, input of measurements not only with the mouse,
the trouble-free modification of the given floor plan, rotating, mirroring, etc., and a good staircase editor
I hadn’t really thought about interior design insofar as I primarily want to "hand-feed" the users the shell construction, but of course the point is somewhat relevant: users should be able to "continue working" on the files later and not have to switch to another software just for carpets and curtains. I prefer to make inputs in 2D, and very much do not want to have to lead the mouse with micrometer precision just to get "whole" real-world measurements at a scale of 1:x. This point annoys me the most with amateur plans: when the walls on the upper floor are offset by two point zero something centimeters from those on the ground floor just because one clicked that way (à la Parkinson-precision). I think cleanly in whole octameters and after all do not want to plan walls with botcher’s gaps, which I always complain about ;-)
Integration of building services, yes, the program should be able to supplement and vary that later according to the user’s taste. My example houses should be "neutral" and at most set up such things as a black box – I do not intend to take sides for any particular heating philosophy (as said, mostly shell construction that the user then "refines" themselves), so I do not explicitly install the Binford 6100 heat pump. Some walls I want to set up from the start as movable objects, namely typical option walls such as those between child 1 and child 2, bedroom and dressing room, kitchen and pantry, or the like. In my way of thinking as a planner, a wall arises in three steps: position, wall thickness, and material.
Rotating, mirroring, yes, hopefully the programs also agree with me that these are absolute basic features. Stairs, yes, also a very good keyword: after all, the "model houses" should also be useful for those home builders who belong to the "XXL ceiling height faction," and that essentially impacts the stairs.
"Scalability" is overall a central point because it should be a help for people with very different tastes and not just produce "houses for 11ant or Nordlys" ;-)