The Westin Berlin is not a top luxury hotel, but it does have a certain grandezza with it's free standing stairways in the lobby and the outside gastronomic areas. More lively - in a good sense - than the rather intimate Regent. More spacious than the Adlon. And the location is unbeatable (right in the middle of Berlin-Mitte; by foot to Brandenburger Tor, Gendarmenmarkt and Potsdamer Platz).

Upside of the Adlon: you can visit the inhouse China Club.

Regent feels more "luxury" than the rest, even above the Rocco Forte.

Ritz-Carlton is the exchangeable Dubai-style.

Hyatt overly architectural IMHO.