I don't think the best of Universal would rank above the best of Disney for me, but I have yet to ride Hagrid's, and have a strong feeling it would be the first Universal ride to break my top ten. Spider-Man and Mummy are fantastic and would definitely make my top 15/20. FJ and Gringotts have really impressive ride vehicles but IMO the overall experience doesn't compare to Disney's best.
I also have no doubt Tower of Terror is 100% deserving of its spot on everyone's lists but I've always been too afraid to ride it! Trying to be objective as possible, my list would look something like this, in no particular order:
1. Pirates of the Caribbean (Disneyland)
2. Haunted Mansion
3. Splash Mountain (Magic Kingdom)
4. It's a Small World (Disneyland)
5. Spaceship Earth
6. Indiana Jones Adventure
7. Mickey and Minnie's Runaway Railway
8. Rise of the Resistance
9. Expedition Everest
10. Flight of Passage
My personal list would include Living with the Land and PeopleMover since they're some of my absolute favorites! And I'm assuming animatronic shows are exempt here, otherwise Tiki would definitely make it in top 10 for me. Also, I've only been to DL, WDW and DLP but I'm sure this list will look very different when I finally get around to visiting TDL. Fingers crossed I get there some day.