I guess this thread consolidates many other threads as people are given the opportunity to post their vote for "best" hotel in various cities around the world.
For me:
London: One Aldywch
Paris: Four Seasons George V
New York: best - Four Seasons favourite: Waldorf Towers
Bangkok: Four Seasons
Tokyo: Four Seasons Marunouchi
Whistler: Four Seasons Whistler
San Francisco: Four Seasons
Vienna: Imperial
Berlin: Four Seasons (now Regent)
Singapore: (tie) Ritz Carlton & Fullerton
Philadelphia: Four Seasons