Universal gets the nod over Disney for us.
The themes of the rides and attractions appeal more to us than at Disney.
The characters (Marvel Superheroes, Scooby & the Gang, the Minions, Shrek, Simpsons) appeal more to us than at Disney. We're just not all about the Princesses and Mickey Mouse.
We like being able to decide where and when to eat (even at a full service restaurant) on a spur of the moment rather than making an ADR six months in advance.
We find the food to be priced lower at Universal and to be of equal or better quality.
We like having the ability to purchase Express if we want it (we are off-siters by choice, but that doesn't mean we don't have a means to deal with crowds if we wish to purchase it. At Disney, we get 3 Fastpasses and then we're on our own).
We find the Universal TM's to be equal to, and often even more friendly than, the Disney CM's. Customer service at Universal has been as good as, or better than, anything we have experienced at Disney too.
We enjoy impromptu character meets versus the long lines we typically find at the Disney parks.
Annual passes at Universal have been within our budget, where Disney's have not.
There are more thrill rides (which my husband prefers) than at Disney. Small World just doesn't cut it for him.
Butterbeer

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Overall, we just find the Universal parks relaxing and spontaneous.....visiting there FEELS like a vacation. We don't get that same feeling when we are planning a Disney day, with Fastpass reservations and dinner ADR's and at least a moderate need for a touring plan in order to manage all the must-do's.
Universal feels like a more grown up vacation to us. We enjoy a Disney hard ticket event from time to time (
MNSSHP or
MVMCP) but otherwise we're happy to take a pass.