SAFD - Great question! I'm going to provide both WDW and DL:
WDW:
1) Big Thunder - this ride makes me smile from start to finish. Pure Disney magic combining thrills, and original theming that to me is a marvel of Imagineering. Its standing goes up even more at night - a great attraction that is even better at night.
2) Splash Mtn - quite easily the best water ride I've ever ridden (I guess it wins that by a mile...)
3) EE - I love this ride, and while I'm a coaster fiend, I must be struggling with going backwards in my later years as this portion of the ride has made me a bit queasy...
4) Space Mtn - a great ride, but I love DL's so much more, esp. with the onboard soundtrack which is huge for me.
DL:
1) Space Mtn - proof that the biggest and tallest coasters aren't always the best. The sense of speed this thing creates in such a tight space (and at relatively slow actual speeds) is a marvel to me. Add in very fun overlays with Ghost Galaxy and Hyperspace Mountain and this is one of my favorite coaster experiences ever.
2) Big Thunder - still great, and at night it is probably #1 for me
3) Splash Mtn - awesome ride, but I like the log configuration at MK better...
4) Matterhorn - a classic... an original... and the updated theming is terrific. If they were able to somehow re-build so you could bank the turns it would probably be #1 for me... As it is now, it is pretty jerky, which brings it down a notch. This probably passes Splash Mtn at night, however, where it really comes alive.