I've been to them all except Shanghai, so I will attempt the same ranking. I'm a big Disney fan and worked at WDW for three years, but never got to work any of the coasters. Don't have some of the family/kiddie creds from my Asia trip a while back due to time. No excuse I guess to not have the Cali Gadget Go Coaster though, just didn't want to wait when I was there this past January.
1. Space Mountain, HK (These Space Mountain's are essentially the same, audio was not present in Tokyo though.)
2. Space Mountain, Cali
3. Space Mountain, Tokyo
4. Big Grizzly Mountain, HK (Great theming, and very re-rideable!)
5. Expedition Everest, Florida (Always enjoy the backwards section, and the night rides are much better.)
6. Rock 'n' Roller Coaster, Paris (I like the theming more in Paris than Orlando. At the concert vs. traveling to the concert. Fog+Lights were nice.)
7. Rock 'n' Roller Coaster, Orlando (Still similar, but theming during the ride feels a little tacky to me.)
8. Space Mountain: Mission 2, Paris (Didn't bother me the way others seem to not like it. Enjoyed the theming the most of any of the Space Mountain's.)
9. California Screamin', Cali (Lots of fun, and very re-rideable.)
10/11. Space Mountain, Florida (Great for its age! Maybe one of my 5 most ridden coasters.)
12. Big Thunder Mountain, Paris (Liked this one the best, though all are similar.)
13. Big Thunder Mountain Railroad, Tokyo (Very similar to Florida especially, but give this one the edge I guess.)
14. Big Thunder Mountain Railroad, Florida
15. Big Thunder Mountain, Cali (Very much enjoy the update to the lift hill, but still the most tame of the four.)
16. Seven Dwarfs Mine Train, Florida (Amazing animatronics, and may be the only coaster where the lift hill is my favorite part.)
17/18. Matterhorn, Cali (Hard to go wrong with this classic!)
19. Crush's Coaster, Paris (Kind of an odd indoor coaster, but wasn't bad either.)
20. Indiana Jones, Paris (Gave this the edge over Raging Spirits just cause I remember a smoother ride on this, but not really a difference.)
21. Raging Spirits, Tokyo
22. RC Racer, HK (Another odd coaster for Disney. Paris one was built after my most recent visit.)
23. Barnstormer, Florida
24. Goofy's Sky School, Cali (Edges out Primeval Whirl as I just find the spinning mouse coasters uncomfortable.)
25/26. Primeval Whirl, Florida
27. Casey Jr., Paris (If you count powered coasters...)