I love all three mountains individually and for different reasons. I also feel that the Magic Kingdom's "Mountain Range" wouldn't be the same without any one of these. The last time I went I went on Space Mountain 4 times and really enjoyed it, I couldn't stop laughing. But I would have to say that I've liked Splash Mountain the most lately, it just has it all. Good animatronics, good songs, good laughs, it's good and long, and good thrills. But you have to respect good ol' Big Thunder too, it's one of those classic old roller coasters.
The Haunted Mansion Bros.