After doing a split stay (3 days at Disney, 2 at US) my hubby, my DD10 and myself all had a better time at US. For us, it is about relaxation. At US, I did not have to worry about FP times or ADRs. We could go through the parks at our own pace without worrying about getting everything in we wanted to. We could decide that day where we wanted to eat. This made our time so much more pleasant and relaxed. I think the theming is great in US- the super hero area is totally underrated. I left US feeling like I did so much. I never feel that way when I leave Disney; I always leave there feeling like there was so much I missed. Part of the problem is our florida vacations are very short (5 days or less) so US is better suited for us.
But I do realize, that everyone has different vacation styles. Our lives are already busy, busy, busy and heavily scheduled. I don't like my vacation to be like that too.
My goal is to do a US-only trip after VB opens.
I couldn't agree more, that Universal lets you have a much more spontaneous trip. I'll see how I really feel about FP+ after my August trip, but right now, I think FP+ is generally a "fail." Though I generally actually like planning, it's gotten ridiculously complex at Disney. One can apply for a mortgage with more simplicity than planning a Disney trip.
I still love Disney but this is a big advantage to universal.
I wasn't a huge fan of the Superhero land -- It was nice and colorful to walk through. But I felt like it truly only had one attraction that really was based on the superheros -- Spiderman. The remainder of the rides simply stuck some minimal superhero theming. (The Hulk Coaster is just a green coaster... Dr. Doom's fearfall is just a regular amusement park drop ride, but with a big picture of Dr. Doom, etc).
The theming of Harry Potter was truly on the next level, beyond anything Disney has done. Mummy, Kong, also had very good theming. Beyond that, personally, I prefer the theming of Disney. And I'm not a thrill ride person -- I do Tower of Terror at Disney for the theming, not for the thrills. But that's just me.