DCA is easier to walk through in the rain. Less slippery and uneven surfaces and you can do a lot in the Animation Building without going outside. TSMM and Little Mermaid are also indoors. Frozen is fairly long show so you're inside for a long time. There's also It's Tough to Be a Bug and the preview in the former Muppet theater. WOC is less likely to be canceled in rain than any outdoor show at
Disneyland. Both parks are lacking in indoor seating for dining, though. I'd probably leave the park for that.