So, as a decade+ season pass holder at Six Flags over Texas, I feel compelled to reply. Again 
The coasters are world class at Six Flags. Many of the biggest, fastest, tallest records are, or recently were Six Flags coasters.
Tallest Roller Coasters in the World
#1 Falcons Flight - Six Flags Qiddiya - Coming Soon
#2 Kindga Ka - Six Flags Great Adventure
#5 Superman Escape from Krypton - Six Flags Magic Mountain. Also one of the fastest I believe.
And then there are largest wooden coaster, largest fastest hybrid coaster, largest loop, there are TONs of other records in Six Flags Parks. The Texas Giant, which was once a record breaking wooden coaster, and now is a hybrid, is spectacular.
To imply they are in any way discount coasters ignores the amazing spectacles many of them are.
They are the best coasters, on average, of any park chain, in my opinion based on records and firsts.
That all being said, Six Flags Over Texas, and most Six Flags Parks (they are all a little different) don't want to invest in customer service at all. It is atrocious on almost all levels. I mean suck-tastic.
So, to work in a "you are correct" I will say, If you average in customer service with coasters, you end up with a mediocre park.
I know you were referring to Disney when you referenced street performers, but I will bring this back to Six Flags with how they have, over the decades, continued to defund live performances/performers. They seem to want to pour all their performer budget into haunted houses (that they charge a premium for) and abandon free classics.
Oh, and the Haunted Houses are world class as well.
Universal had some great ones too.
I thought all the coasters in Uni and WDW where meh. They were fine, but could not compete with Six Flags.
