Agreed.

Definitely St Regis and Ritz Carlton.

The Ritz Carlton Reserve properties and Bulgari also qualify as high end luxury, but they do not participate in the Marriott Loyalty Program.

Many but not all Luxury Collection hotels will also be comparable; I’d take a hint from the higher category list, but the Hotel Imperial Vienna is only a category 6 and yet is one of our all time favorites. Certainly, examples like the Gritti Palace Venice, Hotel Imperial Vienna, Prince de Galles Paris, Al Maha Dubai, Mystique Santorini, Suiran Kyoto, the Chatwal NYC, Hotel Alfonso XIII Seville, Vdema Santorini, etc easily will be comparable to properties in the other luxury brands you mentioned. The Peru Luxury Collection hotels will compare favorably with Belmond, as well.

For perspective, we also stay often at Aman, Peninsula, Four Seasons, Mandarin Oriental, Oberoi, Taj, Belmond, and comparable hotels.

JW hotels are most often affordable luxury with much higher room counts. I generally find even W and Edition hotels are more luxurious than almost any but the newest JWs. If service is your priority, however, I’d avoid large room count hotels of any supppsed luxury brand.

EDIT: there also are a few Design Hotels that qualify as luxury comparable to the brands mentioned. Just know that they have limited participation and benefits with the Marriott Loyalty Program.