I love them all, but voted for Expedition Everest since it's new (to us -- never did get to see Yeti in A mode)
I loved Space Mountain before I had knee problems and didn't have difficulty climbing out of the rockets at WDW, so I can no longer ride it. I don't have this problem with Disneyland's SM, but I like the track at WDW better. My Dh's favorite is Big Thunder.