I know my #1, but the rest is tough
Splash
Everest
Thunder
Space
None of these should be #4, but one of them has to be. I guess I pick Splash because of the wonderful theming of the ride and the length as well. I've always described it as peaceful as Small World with a nice drop at the end. Plus that view at the top just before you drop, wow!
Everest is the most thrilling out of the 4 from a raw standpoint. I'll never forget my mother screaming blue murder because she literally thought the track was torn apart and we would fall right off. But lots to like, it stands on its own as a thrilling ride. That downward spiral in the dark is epic.
Thunder is the first rollercoaster I fell in love with. I love the twists and turns and the theming is great.
Space is #4. I don't know why. One of them had to be. I love the dark factor. I love being cranked up in the beginning in pitch darkness. And the kicker, you are going as slow as molasses (28 mph). But you never know it, in the dark and with the effects. Not to mention you swear you are going to bump into other people.