Which furniture stores can you recommend?

It comes from psychology and describes the phenomenon that the brain rationalizes conflicting cognitions in such a way that one does not notice it oneself. You actually don't want to spend that much money on a piece of furniture. You want a piece of furniture that you like, but it is expensive. Then it obviously has to be of higher quality and all the other, cheaper pieces of furniture were much worse. I would bet that one or the other cheaper piece of furniture would have lasted seven years anyway.

It comes from psychology and describes the phenomenon that the brain rationalizes contradictory cognitions in such a way that you yourself don’t notice it.
You actually don’t want to spend that much money on a piece of furniture. You want a piece of furniture that you like, but it’s expensive.
Then it has to be of course of higher quality and all the other, cheaper pieces of furniture were much worse.
I would bet that one or the other cheaper piece of furniture would have lasted at least seven years.

And that is exactly what I don’t believe. If you read carefully, the purchase of the expensive sideboard was not driven by "liking." We have seen many beautiful things that we really liked visually for much less. The workmanship is simply lousy. When I touch the display item, operate it, and then realize that everything wobbles and rattles, that the veneer has the quality of paper and is wavy, then that is money thrown away.
The point is, it is not supposed to last seven years. It is supposed to look like new after seven years and last 20-30 years.

That is the beautiful thing about the brain it cannot always distinguish between before and after. This, by the way, is not just psychological theory but supported by neurological studies. But let's better end the off topic, otherwise we might get kicked for spam.

Now that we have found our house, I want to focus on good quality but not pay an extreme amount for the "name," just reasonable prices for the quality

The tips have already been given: go out, visit stores and take a look. Maybe before that, consider over a glass of wine which style is acceptable. For example, you can also buy a few home magazines. There you can get inspiration like on Pinterest and there are also tips for purchasing. So: go out, touch, compare quality. And also set the price aside for a moment. There is no rule that a table between 1500 and 2000 is valuable and worth buying. A 500€ table can look nice, a 2000€ table can look awful. And if the 1000€ good table starts to wobble in 10 years, then you tighten the screws. If you no longer like it or it is worn out, there is eBay for that. I also wouldn’t buy a book or ...

We are looking for furniture that looks timeless and elegant. For example, white furniture with wooden accents

I can’t relate to that at all... and I am quite open-minded when it comes to interior design :) The latter reminds me of Scandinavian style. But Scandinavian is not elegant. For me, elegant would be English style or somewhat polished antiques, but that is rather brown and wood-heavy... The latter, meaning white with wood, would be Ikea again... I ultimately can’t imagine you in a store at all. How do you live now? Photo????… !!!!!

What kind of nonsense do I have to read here again, unbelievable… …and exactly these pieces of furniture are available as a bargain :D

If you had really read the thread, you would have noticed that the OP's requirement is for a good price/performance ratio with high quality for the furniture purchase of an unspecified shopping list with a budget of up to €40,000. There is certainly room to suspect that this is above the bargain level.

We are looking for furniture that looks timeless and elegant. e.g. white furniture with wood accents For the interior design, we have planned around 30-40K€ We simply find it difficult to find out with which furniture manufacturers we get good quality at a reasonable price or where we should start our search ...

I would also inquire at a carpenter or similar. Our next living room furniture will very likely come from there.