Variants of basement construction (Pour concrete walls in the middle?)

Insulation has nothing to do with barriers. First, one would have to check the soil report to see if there is pressing water; that already influences the method of execution. The sealing has been newly regulated in DIN 18533 for some time now. At the moment, we are dealing with too many variables.
Oh, and the masonry basement still exists, of course.

According to a well-known architect, masonry basements are no longer common in our area (BaWü) because the prefabricated walls are supposed to be faster and also cheaper.

Thanks for the answers.

what do such sealing strips look like, or how are the individual prefabricated walls then sealed? Do you know the approximate page number of your thread about that?

Unfortunately, I can't tell you the page number. You have to flip through a bit until you reach the shell construction. The wooden walls are sealed before filling. The earth-contacting ones, such as basements, are additionally sealed after filling. We wanted the concrete look. It is true that basements are rarely masonry. Either such element walls or classic formwork. There are also element walls with integrated insulation. It's called Thermowand. We originally wanted to use this. Due to our special window system, it was not possible. Do it as the construction company always uses. Overall better with the existing experience and therefore also cheaper. I see both newly built basements with shuttered walls as well as element walls in the area. However, element walls are in the majority. I don’t know where in BW you are from, but for example, there is a manufacturer in Geisingen (near Lake Constance).

2) the prefabricated basement (there are prefabricated basement walls, which are placed in their respective positions by crane) 3) what I was recommended by an acquaintance: a type of concrete wall formwork (no metal plates that are dismantled after the concrete hardens), whose interiors are then poured with concrete.

"2" I haven't seen in other variants for ages than what corresponds to "3". With (transp)ort concrete filling, it is much more practical: the wall panel is significantly lighter as long as it still has to be transported or moved, and in this variant the wall virtually brings its own "lost" formwork along. In addition, there are formwork stones, where a lost formwork is "masonry stone by stone," this is the most suitable form for do-it-yourselfers.

Where is the house described regarding the basement question?

Yes, it may be that 3) (Elementwände, Hohlwände) has become established. The acquaintance also said that most construction companies currently do it almost exclusively this way.

Since 2) (Massivwände) is still being offered, I just included it.

I did not include the house here.

...just as a note from personal experience... I would be surprised if the hollow walls are actually supposed to be cheaper than cast-in-place concrete. Personal experience because I considered both myself and likewise multiple times in the neighborhood with different construction companies. On the contrary. Prefabricated elements are a significantly more expensive piece.

Edit: Likewise in BW

Have you also taken into account that with a shuttered basement the interior walls cannot be painted immediately (requires plaster + work) and that the window openings have to be made afterwards (work)?

Do you have concrete numbers? Unfortunately, I do not, only the experience of several construction companies that now almost exclusively do it this way with element walls. Or what could be the advantage of element walls instead of the shuttered variant, which (increasingly more) rely on element walls?