I called Hyatt to fix something - I started speaking as if to automated machine. Imagine my surprise when an actual human answered. She fixed nights, points and promo points all at once immediately on phone. My acct updated while talking to her.

Marriott? 8 days to get a response for me to email a different email address about a missing stay.

I still prefer Marriott's collection of properties and on property experience but Hyatt CS far far far superior. They are able to fix problems immediately.