Earlier this month, we did a Ohana breakfast and an early Crystal Palace dinner less than 24 hours apart from each other - so it's easy for me to compare! We have three boys, but our youngest son is similar in age to your kids.
Ohana breakfast: We absolutely loved Ohana for breakfast and will go back again next month - very relaxed fun atmosphere, Mickey, Pluto, Lilo and Stitch, great service, great view of the castle from our table and a good variety of breakfast foods. The service was really some of the best of the entire trip - so friendly and not a bit rushed. It's also served family style so your entire family can sit and the food comes to you - rather than taking turns with the kids at a buffet. Our pre-schooler also enjoyed the parade and marched right along with Lilo for part of the time.
Crystal Palace early dinner: We enjoyed Crystal Palace, but it was far more hectic than our Ohana breakfast. I liked the salad bar items and the dessert, but wasn't a fan of the hot items on the buffet. (I've read that the main difference between lunch and dinner is fewer entree or meat choices, but I can't confirm.) Our wait for a 4:40pm ADR was a bit long and it was very busy inside. We had a great time and our pre-schooler loved the characters - was thrilled to participate in the parade with Pooh! We were ready to go before all the characters arrived to see us, but that was easily remedied by informing the nearest CM. But it's not on our list for the next trip like the Ohana breakfast.
So we thought the food, atmosphere, characters, service, etc. was better at Ohana breakfast. And that's saying quite a lot because I'm not much of a breakfast person in the first place!
Hope that helps a bit!
