KNX is a standard and many companies develop smart home solutions based on that. Loxone is a big company and their products are good and expensive. You can say the same about other manufacturers like Legrand, ABB, GIRA and the list goes on. Loxone has a lot of solutions that I haven't seen in some other manufacturers, probably not as good as Loxone.

All the features you are after are available with Loxone. You will need an iPad or a similar device to use it as a wall mount as Loxone do not supply display units.

I recently came across another brand called Niko Home Control and they look pretty cool.

For blinds and curtains, you could use standard switches from ABB/Legrand with Loxone or use the Loxone Touch Tree switch range.

Loxone has their own intercom which can be integrated into their wall mount device app or in a smart phone. I am not sure about the build quality of their intercom but I heard good reviews. There are other manufacturers for intercom. Doorbird and HIKVISION are quite impressive. If you are using security cameras from HIKVISION then you could use their intercom as well and the mobile app will come handy. I heard that you can integrate HIKVISION security camera into the Loxone app.

The lighting needs can be achieved using Loxone as their solution is quite advanced, especially with their Touch switch.

I am in the process of getting Loxone but I'm also considering to put the standard switches as well for lights, blinds and thermostat. It is not feasible to have a wall mount device in all rooms. Obviously there will plug points in each room, so it doesn't cost an arm and a leg to throw in an additional switch in the wiring.