WAFLD: Runaway Railway. Although I should experience it well before race weekend.
Space Mountain is extremely smooth in DL. I never miss it. But I can skip it in WDW and no big deal. In a sense, it's a completely different ride albeit with the same theme.
Haunted Mansion is similar with some differences. But assuming that the Nightmare Before Christmas overlay is still up, it very much changes the ride itself.
One thing that I love about
Disneyland is just how much attention it gives to Fantasyland. While new Fantasyland in the MK is great, the older part of that Fantasyland feels like rides put into a generic box facade.
Disneyland has different building facades for each Fantasyland ride instead of the ride in a box of most of the MK. Small World itself is a key part of the Disneyland skyline if you will.