Universal Orlando

Disney hotels are pretty good - but now you have to pay parking, and, to my knowledge, the only upside to staying at Disney (aside from proximity and sometimes transit) is some extra time in the morning. As far as budget goes, you’re probably best off staying off-site. The hotels are still exceptional - might be worth finding your way over to one for a dinner or something.

Now, Universal is a different story. While staying at the Hard Rock, Royal Pacific, or Portofino Bay hotels may be notably expensive, it comes with a ticket to pretty much maximizing your Universal experience: Unlimited Express Pass for the duration of your stay. Even if just one day, you get to go through every available priority queue as many times as you want. It’s kind of incredible, to be honest. And that’s on top of being in super close proximity to the parks (and CityWalk, essentially a plaza full of various shops and eateries), and one hour early entry.

You don’t have to spend the whole stay at just one hotel though. I’d advise dedicating 1-2 days to Universal (you can easily do both, even Hagrid and Velocicoaster with a park to park and Express Pass), then doing the Disney days through some other method.

I’d advise going to a more Disney-centric sub for advice on them.

No reservations. Go whenever you want. That and it doesn't require a micromanaged day where everything, including quick service dining, must be planned in advance.