If you’re going to increase the budget anyway, then just go for the classic among chairs: the Thonet cantilever chair with wicker. Totally comfortable and beautiful (expensive ;)).
Design is debatable; I don’t find it beautiful.
In general, no expensive furniture comes into my house; ideally, it’s quality but inexpensive furniture.
You get tired of it too quickly anyway, and it’s a utilitarian object. Besides, with a bit of research, you can always find great bargains.
And if you have the necessary budget, then definitely only custom-made furniture from a trusted carpenter. Super individual according to your own taste.
For example, I consider spending more than 150 euros on a dining chair absolutely excessive. Or a couch for over 2000 euros. It can’t be that high-quality; it strongly smells like rip-off or brand fetish. I’m basically out on that :)
Although furnishing an entire house, I think 15,000 euros without kitchen, without bathroom is quite realistic. Maybe even too cheap; it will be very difficult even with 100% IKEA.
Office, dining room, living room, bedroom, 2x children’s rooms, pantry, wardrobe come to mind. That would be max 2000 euros per room. I think that’s almost impossible.