I agree that it's hard to go wrong with Chef Mickey's. There are other places with better food but CM's is a lot of fun and you get Mickey, Minnie, Pluto, Goofy and Donald.
I think it depends mainly on what characters the kids want to meet. We also really love the breakfast at O'hana. They have Mickey, Pluto, Lilo and Stich.
All the character meals are expensive but it's a really nice splurge. If you want to save a few dollars here's my advice.....
Make your breakfast ADR at Chef Mickey's(or O'hana...they are both at monorail resorts) on a day when it is EMH morning at MK. Get the very last time that they have, it will be around 11am. Get up early and have a snack in your room then go and enjoy the MK until about 10:30am. Head over to CM's for you 11am ADR. If you arrived at MK around 8am you will be ready for a break and an early lunch by your 11am ADR. After your meal you can either go back to MK for the rest of the day or you can return to your room to relax for another few hours before going back to MK for the evening. If you have park hoppers you can go to which ever park you like.