Personally, what I expect from a Universal/Disney coaster (and any other ride) is clear storytelling. The coaster is the ride system, not the whole experience.
As far as Epic Universe coasters, Donkey Kong already seems highly likely to have great storytelling, and I'm confident the others will as well. Incredible themeing, like rock work, a temple, or a space station certainly helps the storytelling, but you have to use it. The status quo has to change (that doesn't mean something always has to "go wrong" lol).
Again that's just me personallly, not any "official" definition lol. Love to hear what everyone else thinks