as for me, I switched from Marriott to Hilton five years ago and have not looked back.
Hampton and Hilton Garden Inn are far superior to Fairfield and Courtyard.
The Hilton properties I stay at run circles around any of the Marriott's I used to stay at. Plus the other brands of Embassy and Double Tree offer lot's of competition for inner brand pricing. (I can often find Double Tree or Embassy at the same or lesser price than Hampton.)
I would get an upgrade 5% of the time at Marriott versus 90+% with Hilton. No Blackout dates, effective customer service (everyone here says they are bad but I have never had an issue with them.)
Down side; their website sucks!