Which one is the best park for 4year old twins, I want them to be able to ride and play on everything

Definitely Disneyland.

Disneyland has a muchi wider selection

Disneyland has a wider variety of rides for younger children, but if you're asking about a specific area, I would recommend Fantasyland, Main Street, and Toon Town. These have very kid-frindly environments and offer rides better suited for their ages vs more intense rides. Main Street doesnt have rides, but they can enjoy the horses and ride around the area. I would also recommend the Tiki Room for a good sit-down attraction and Dole Whip if they can eat it.