Which smart home system is suitable for our new building?

Whereas I believe that with f@h, even €10,000 is just scratching the surface. Let's not kid ourselves, the expensive part of a smart home with cables is also the cables. Bus cables have to go, at least partially, into conduit; the electrician can also charge for 5x1.5 instead of 3x1.5. Are the €10,000 actually already including additional requests for the "normal" installation? Depending on your requirements, you can easily sink another 4, 5, 10,000 euros. An extra socket costs me €33, a data socket €131 net. I then decided to take many singles and later expand to double or triple myself if I notice that I need more.

with the 10,000€ for F@H you should roughly get by according to the electrician

The 10,000€ is really only for F@H, the rest will be charged separately
Your electrician has even better prices
We pay 65€ for individual sockets: CAT-Duplex 250€ net
We will also do many sockets ourselves, so expanding from 1 socket to 2 or 3 is not a problem
or placing a socket under light/shutter switches

Unfortunately, we have to use wireless then, 20,000€ is unfortunately too much for KNX and I don't think the 10,000€ for F@H is worth it because F@H has too many limitations which won’t make you happy either

May I ask you something about the video doorbell?
We now want to take a WLAN video doorbell that then integrates seamlessly into the smart displays (Amazon Echo or Google Nest Hub)

At what height would you mount the cameras? 1.50m?

For that we also want to take the new ekey xLine (when it finally comes) which would be mounted at about 1.20m or 1.25m

According to the electrician, one should manage with about €10,000 for F@H

Since F&H is more expensive than KNX with an appropriate comparison, this statement by the electrician most likely indicates that he has little or no experience with KNX or simply lacks the necessary qualification and has to acquire experience. However, he can do F&H himself and thus offers this.

When it comes to WLAN doorbells, video, etc., I'm out, my hobbyhorse is more the socket. Alexa, Nest Hub or something like that won't come into my house either. Always remember, once your smart home controller is connected to the WLAN, an attacker can cause any kind of mischief... And with ekey it quickly becomes very critical because if that's hacked, the place is open... without signs of a break-in, which every home insurance company loves because then they don't pay. I will configure my Bosch Smart Home (by the way, Bosch is involved with Matter, the new Zigbee standard) and then I pull the router. From then on, it will only work via radio and corresponding control elements that I have preconfigured. I don’t plan a complete operation via app, simply because then the kids won’t be able to turn anything on anymore :D But this pricing is already interesting. A double socket is by no means 4 times as complicated as a simple one. He has to chisel the slot anyway, he also has to set the socket, a double socket doesn’t cost more than a simple one... well, he has to pull a second cable... He probably does that because many think they absolutely need double sockets... which is nonsense in my opinion. But okay, those who have them ;)

It may of course be that he is not very familiar with KNX and has to buy the information, or he simply doesn't feel like it. The electrician is, however, KNX certified.

Which doorbell do you use? But I think 1.50m height is okay and you can't really do much wrong, can you? Echo Show or Nest Hub the displays are supposed to become the smart home control center and would replace the tablet on the wall.

What bothers me about Bosch (and many others too) is that you still need their gateway and that with the new devices they don't directly use Thread to be able to omit the gateway.

What do you actually think about EnOcean technology? Will it be able to coexist alongside Matter or will Matter eventually replace everything?

The ekey is operated separately (so not connected to Alexa).

What do you actually think about EnOcean technology? Will it be able to coexist alongside Matter or will Matter eventually replace everything?

Matter won't replace anything. It is simply another standard alongside the ones already existing. EnOcean has its fans and will continue to exist there. The downsides are the haptics, design, and noise generation of the components. Otherwise, it is a good system for cable+radio mix enthusiasts.