River wins in landslide. Grizzly River is a terrific ride, hands-down the best ride of that 'genre' of rides... but you do get wet, so a lot of folks skip it. Kali Rapids is a pathetic ride, one of the worst of that 'genre' of rides. I'd say 'skip it' entirely, but it's probably one of the top five attractions in Animal Kingdom.

As mentioned above, Pirates of the Caribbean is much better and longer at Disneyland.

The Tower of Terror at DW (Hollywood Studios) has varying settings, so you get a slightly different ride every time. The DW version also has the '5th dimension' corridor, which is cool. The Tower of Terror at DL (California Adventure) is the same exact ride every time.

Space Mountain is much much better at Disneyland. You sit side-by-side instead between each other's legs. The ride is smoother, so you get less whiplash.

Buzz Blasters - better at Disneyland because you can pick up your gun.

Splashmountain - I'm having trouble remembering any differences, but I have relatives who swear the DW version is better.

Big Thunder Mountain, Tough to be a Bug, Toy Story Mania, Star Tours, Jungle Cruise, Soarin, Little Mermaid, various Fantasyland rides that are in both (although DL has more unique rides in Fantasyland), Haunted Mansion, are basically the same.