Wallpaper or plaster? Which is better in new construction?

Thank you for your help

can you recommend a brand for the primer and adhesive?

Should we use a deep primer or wallpaper primer? Are the primers also vapor-permeable?

I used Metylan fleece paste. It's just expensive. There are probably cheaper options. I used Tiefengrund from Alpenkalk. I don't know if there's really a difference from wallpaper primer. You'd have to look at the technical data. For the effect I wanted to achieve, water would probably be enough.

Did you use ready-made paste or mixed it yourself?

What exactly is the [Tiefengrund] supposed to do? Just bind the dust from sanding on the wall? There are so many differences, as a layperson you have no clue at all :((

I searched for the right fleece, where we can buy it, I saw prices around €0.90-1.00/m² on average

The Erfurt wallpapers in the larger packs were often cheaper or similarly priced at about €0.90-0.95/m² compared to other brands like Proofhome or HOMEFACTO:RI or other no-name products from the hardware store

So basically, it's a no-brainer to definitely go with the Erfurt wallpaper, right?

Both. Mixing it yourself is not so difficult, so the cheaper price is worth it.

Normally, Tiefengrund is supposed to even out the absorbency of the substrate. So initially, it absorbs differently everywhere and that naturally changes the painting pattern when painting directly. But with gluing, this is not so important. The main thing is that it sticks. The paste is also not absorbed as quickly because it is much thicker.
For me, it was mainly about dust binding.

Yes, if the prices are like this now, you can probably use Erfurt as well. For me, it was 50% more expensive back then.

We are considering whether we should have the wallpapering done by a painter.

Can someone of you tell me approximately how much it costs when a painter wallpapers with [Malervlies]? (I just want an approximate guideline)

Just the wallpapering, we would prepare everything as well as possible to reduce the costs a bit.

Prepare the substrate as well as possible (smooth it with filler and sand it as much as possible) and tape off the windows, doors and so on.

In the end, we might possibly paint over the [Malervlies] ourselves (if there is no money left for the painter to do that).

I also consider it sensible, but it strongly depends on what offers you get.
In the end, I had 200m² wallpapered because I ran out of time and coincidentally still had money.
However, it was with only one round of filling and sanding for 20 EUR/m². The work was not perfect either (one or two slightly uneven strips, a handful of slightly loosening edges), I probably would have done it more thoroughly with my standards, but I would have needed four times as long (if that is enough).
If you have already prepared the substrate and really only wallpapering is done, it should be significantly cheaper with painter's fleece. I would estimate 10-15 EUR.