Most of us aren’t music experts, history experts, or architectural experts; but we do know a good experience when we encounter one. So this is really about a music experience in a place famous for music, which is not necessarily about the best of anything. Our lack of knowledge is demonstrated in that the thread has conflated Opera Houses and Concert Halls.
In the Germanic world I vote for the Wiener Staatsoper as a great classic music experience but of course its the only opera house I have been to in the Germanic world. The others were Milan (but so many decades ago, I really dont remember much), Prage, Bucharest, Lviv, Odesa, Budapest, D.C., NYC, San Francisco, moscow and if I compare to those, it was still a splendid experience ... maybe tied with Odesa and Budapest on the count of "classic music experience".
But if you are a music nerd and you do want the best acoustics for classical music without regard to how good the orchestra is, then one expert analysis says:
- Royal Albert Hall, London
- Concertgebouw, Amsterdam
- Berliner Philharmonie
- Philharmonie de Paris
- NOSPR Katowice Concert Hall, Katowice.
https://www.rockfon.co.uk/about-us/blog/2022/top-5-concert-halls-for-the-best-classical-music-experience/
Even then, as different masters wrote different pieces to capitalize on the acoustics of different concert halls, there really is no "perfect" hall for all pieces.
