Best to worst in my opinion:
1. Disneyland (the original, small but packs everything in well which is something I like, has great exclusives like the Matterhorn, park always has a happy atmosphere)
2. Magic Kingdom (Bigger but not necessarily better version of the above, I love MK, but it's stagnating and needs major investment)
3. Disneyland Paris (beautiful park, by far has the best Space Mountain, Big Thunder Mountain, Pirates of the Caribbean and Haunted Mansion, but the years of neglect, no new attractions and misbehaving locals and miserable CMs bring it down)
4. Hong Kong Disneyland (lacking several classics that make the 'Disney' experience but otherwise now a good park)
5. Tokyo Disneyland (very dated, odd layout, lots of open empty concrete space, ugly, really don't care for this one)
6. Shanghai Disneyland (lacks everything I expect from a castle park, not always a bad thing but I have no interest in visiting)