I believe that in Paris, there are 2 places worth mentioning:
1/ Le Grand Rex
This place really feels like a natural choice for premieres due to its unique look. It’s a big theater, with leather seats & a retro atmosphere all around. I’ve been to this place for several premieres & events, it always feels very special.
They have 2 screens available (they can switch between those before a screening). One is big, the other one is huge (not IMAX-huge though).
That being said, its probably not the best choice on a technical side. Image quality is good but the sound is a bit weak in volume since its such a big theater (it especially feels distant on the balconies). Also, the surround effects tend to blend too much with the other speakers, meaning you don’t get a very wide audio scenery.
2/ Gaumont Champs Elysées Marignan
Located on the famous “Champs Elysées” avenue, it’s actual a twin theater (on both sides of the avenue).
The “Marignan” side is the one to pick. I think it’s very telling they hosted several official premieres in the past for directors reknown for their technical obsession such as Christopher Nolan & Peter Jackson, and lately with the 70mm showing of Quentin Tarantino’s “The Hateful Eight”.
It’s a smaller theater but with great picture & sound accuracy (sorry no Dolby Atmos though). Their projectionist team is very professional and caring.
The only downside, is that its much more standard-looking inside and thus feels less like the “big event”. It’s still classy there though!