It's very hard to say, IMHO. With regard too the "big 4," I used to really like Marriott (#4), but now have dropped to MR, CM Gold as I've been recently increasingly disenchanted with them, and while I'm also only Gold with Hilton(#3), they are seemingly improving in every way in my book.

As a Starwood Platinum and Hyatt Diamond, they would likely rate #1 and #2. FWIW, customer service and availability of quality hotels with good locations, excellent food and service at the best value are what I'm after - that and upgrades!

BTW- Likelihood of upgrades to Club floors at these properties according to recent data revealed to me by Randy (at live chat 8/15) are Marriott (nearly 90%) > Starwood > Hyatt > Hilton (75%)

So maybe I should have stuck it out with Marriott!