I'll say this. The Marriott forum is littered with complaints about elite benefits failures. Upgrades denied, late checkout denied. The Marriott breakfast benefit is highly complex (check that thread out!) with the ~30 brands landing into 6 categories of benefits, except some brands split across 2 categories, and even at the lowest category, a $10 credit that can be used by buy packaged goods, some hotels are failing to meet even those terms.

It's terrific if your experience has been consistently positive, but I'll disagree with an earlier poster that it's just luck. I think there's a wide variance across geographic regions, and also still variance between legacy Starwood brands and legacy Marriott brands. So if your stays to date are typical of your stays going forward, sticking with Marriott may work well for you. Just don't be surprised if the domestic Marriott doesn't treat you as well as the Asian Starwoods have.