I have eaten at all 5 restaurants you mentioned. They all have something good about them, so its really hard to choose!
Crystal Palace is great for dinner. The atmosphere is great, and if you love the Pooh characters, this would be a good choice.
The Garden Grill is probably the bottom of my list. It's cool that the restaurant spins, but its not the best layout for meeting characters.
Tusker House is one of my favorites. The breakfast is really super yummy, and the coffee is so delicious. Plus they have this juice that is really good.
1900 Park Fare is super fun for dinner. As quadsthen1 said, the sisters are hilarious! The food is pretty good too.
Chef Mickey's is just a classic. I'm not a huge fan of the food, but its the best place to see Mickey and friends for sure.
So, if I'd have to choose, it'd be Donald's safari breakfast, and Crystal Palace.