First choice...Cinderella's breakfast (this has to be booked 180 days in advance). We do this everytime we go and our kids love it. The food is ok but eating in the castle with all the princesses is just way to cool!! (Great idea for this is to book as early in the am as possible...the photo ops of the castle and of the Walt/Mickey statue are awesome because the park is empty!!!)
The Norwegian restaurant (name escaping me) is a tie if you want princesses. we have never eaten here but the reviews haven't been bad.
Personal favorite...1900 Park Fair at the GF. Awesome food and great resort
to walk through, character selection so-so (last time we went is was Alice,
Mad Hatter, and some others). This is the best breakfast buffet in WDW in my opinion.
You could also consider Chef Mickey's at the Contemporary...never eaten there but have heard good reviews. Ohana's at the Poly is served family style and that restaurant has a great view of the castle. Aloha Minnie and freinds at this one.
...Ok this isn't helping, is it?

Try this: Pick the character breakfast whose characters best match the kid's liking. Our DD loves the princesses, and our boys love the castle, so it's easy for us. But there are lots to choose from. Good luck and have a great time!
Bob.