I prefer Matterhorn. I adore the mountain itself; towering over everything, visible from Main Street, and photogenic from every angle. It tickles me that WED built the thing in 1959, setting the precedent for concealing the bones of large-scale thrill rides within gigantic faux-natural structures.
The coaster itself is such a delight. There's something magical about the clunky way the trains pick up speed as the track weaves through the structure. I've ridden so many times and yet the layout remains unpredictable (and totally bizarre). Bob Gurr says he taught himself trigonometry in order to design the Matterhorn... um, it shows.
Its only shortcoming is its lack of any real drops. It Matterhorn had just one moment where riders turned a tight corner and suddenly dropped 30 feet (which would be quite a surprise amongst all the turns), the coaster experience would be unimpeachable, IMO. If Imagineering ever bulldozes and rebuilds the thing (because, as Jim Hill has put it, the current structure is supported by folding chairs and rubber bands), this would be my only recommendation.
I love the music in the loading area, and the sounds of the waterfalls and "wind." I love the absurd single-file coaster trains. I love the cast member outfits. I love the thematic dissonance of the Monorail passing by. I love the mystery of what exactly is happening within this mountain. Okay, this is turning into an unsolicited dissertation; my apologies. Perhaps I miss Disneyland more than I realized.
I'll add that I don't find Matterhorn prohibitively rough. I'm a coaster fan; perhaps I've built up a tolerance for painful thrill experiences. I'm also a big fan of Space Mountain at Walt Disney World (and find it much more thrilling than Disneyland's version), which shares some DNA with Matterhorn. Perhaps I just find the bumpy, single-file ride experience more thrilling than the super-smooth, super-safe feel of Disneyland's recently re-tracked coasters.
My somewhat hot take is that Big Thunder Mountain Railroad and Space Mountain at Disneyland are both fine attractions, but they're nowhere near the top attractions in the park, and they pale in comparison to their East Coast counterparts due to their smaller scale. For the "mountain" attractions, size/impressiveness is critical; there's something awe-inspiring about riding the Liberty Belle past the towering rockwork of BTMR and watching the coaster train speed down toward the river -- and something equally unimpressive about Disneyland's BTMR's lack of height/elevation. Disneyland's BTMR earns points for its queue, outdoor load area, and truly fantastic third lift hill, but ultimately I find the attraction somewhat less immersive and thrilling than its WDW counterpart, and less fundamental than the Matterhorn.