My SPG stays are usually cat 5 and above, and from my limited experience with Marriot (2 years as plat in 2007-8, I switched my stays to Hilton after that) it is going to be worse than SPG.

With Marriott, I never got a suite upgrade. Forget late check outs (which could be very useful for weekend nights). SPG has SNAs and reasonable cash and points rate- I recently tried to upgrade a stay at a London Marriott to a suite and the copay was higher than the rate of the suite (suite was GBP 800, I could book the same with 45000 points plus GBP 1000 cash). I ended up transferring all Marriott points to BA.

I have been a Hilton diamond since 2009. I snatch suites once in a while as Hilton diamond (nowhere as close to my SPG experience still way better than Marriott) and late checkouts never have been a problem- except the recent devaluation which makes redemptions way too expensive.

Hyatt does not have the footprint to fit my travel pattern, so I guess it will be a combination of Accor (mainly Sofitel) plus Hilton post SPG Marriott merger going forward for me- unless they seriously rejig the Marriott program. Thankfully I am Plat with Accor now as I diversified post lifetime SPG Plat.