I'm a lowly Silver so I don't get many freebies but I have found Marriott to be the most consistent. They are not perfect but in general are out to satisfy their customers. Whenever I have a significant problem I either bring it up directly to the hotel or write an email afterward and I always get a personal response and compensation. A recent stay in Maui is proof of that.
Hilton recently turned me off with problems with a points stay in Paris. If the hotel experience wasn't bad enough (it was in poor shape), customer service really didn't care. On that same trip I went from a great stay at Marriott County Hall to a disaster at the Paris Hilton. Marriott's have my business...