Although I much prefer DLR to WDW, I have to say Expedition Everest wins hands down. AWESOME RIDE!
But, I really don't think it is fair to compare the two. Expedition Everest is a newly built roller coaster, while the Matterhorn is an old style.
I like the Matterhorn - even though it tends to give me a headache. But the two times I have ridden EE were great!
But they truly are different rides.. One as mentioned is a newer roller coaster themed ride.. the other is many moons old... a bit rougher and not as fast or thrilling..
But it depends on what you are looking for in a ride.
No question...Expedition Everest...but it is an apples to oranges comparison.
Expedition Everest is the best coaster I've ever been on. The combination of the ride and the theming (both on the ride and in the queue) creates an absolutely perfect ride experience, IMO. The Matterhorn is a good ride, but it is 50 years old and it shows.