I choose the location first, and then check on FlyerTalk which hotel shall be preferred.
Speaking about Aman it happened that I chose the hotel experience before the country / place to visit (Amanbagh, Amanjiwo, Aman Sveti Stefan, etc.)
And last, in some cities, there are no brainers for me => Bangkok means MO, LA means Hotel Bel Air, London means Bvlgari
I am still struggling for selecting a nice place in some cities where there is no obvious choice (Singapore for example) so I tend to try 4-star hotels. I know it won’t be great but at least I am not disappointed as my expectations are low.