We did both back in December and loved both.
Tusker House seemed to have a much larger buffet and the food was great. The advantage to being in Animal Kingdom early is getting on the Safari Ride without much wait first thing in the morning because the ride's entrance is very close to the restaurant. You take a pic with Donald out front; Mickey, Daisy and Goofy are inside.
Crystal Palace had the basics (fruits, breads, pastries, sausage, eggs, bacon, gravy) for breakfast (plus puffed french toast - but I'm allergic to cinnamon - and the breakfast pizza - which I don't care for). However, it does have a made-to-order Omelet Bar and those were delicious. Your characters are Pooh, Piglet, Eeyore, & Tigger. We checked in around 8:05am, finished around 9:10am and headed to Dumbo and only had a minimal wait. This was true of most rides at that time.
You might see which characters your kids would rather see. We will do both again, but my favorite was Tusker House. (FYI - Lunch at Tusker is wonderful also, but no characters.)