Interesting that others have had better experiences with Hyatt Concierge than Marriott Ambassador. For me I am still getting far better service from Marriott - maybe I just had a string of bad luck with the Concierges that I had in the past.
If my Hyatt Concierge was better then I would move a decent number of nights away from Hilton and Accor to Hyatt but that has not happened yet.