We have been to Tusker House for Donald's character breakfast once and to Y&Y several times for lunch. TH was a buffet but Y&Y was not. I thought TH had a few suprising offerings at the buffett but Y&Y's menu had more varied offerings which was great because my wife and I are pretty adventurous when it comes to eating.
TH was very loud and crowded, but the kids loved the character interaction and that made it worth it.
Y&Y is usually love it or hate it when it comes to reviews. We like it though and it would get my nod if I was choosing.