This is just my opinion, but I have done all the character meals in the last 9 months on various trips.
The number one on my list is Minnie and Friends and it's for a number of reasons.
1. It's in the park so I can do a Magic Morning or anything else and not have to leave for a meal.
2. More characters than any meal by far, we had more then 12 the last time we were there and have never had less than 10.
3. Price is the best
4. The only restaurant I didn't have to ask to get my button.
If I were to rank them I would have done Lilo and Stitch next, it was AMAZING, but it's now been replaced with Mickey and Friends to draw people over there and it's very busy now so the character interaction isn't as long as it was with Lilo and Stitch. When it was Lilo and Stich I literally got to eat with Daisy Duck (my favorite charcater) and spend tons of time with them all. We also got great large group shots with all the characters too!
The new Mickey Breakfast though is the only meal that Mickey is at so if that is a priority then I would say go here, the servers and food is great.
After that I would say Goofy's Kitchen. I know most people would disagree, but I really prefered their dinner to breakfast. But this is a preferance thing! Great meal and service no matter what!
We really loved the characters at Storytellers, but the food was subpar and the wait staff was not friendly. This could have been a one time thing, but my niece said she would rather go to Minnie and Friends or to Mickey and Friends for breakfast next time and save money. (She is 10)
Finally, I think Ariel's grotto is overrated. I have eaten here 3 times for dinner/lunch and 2 times for breakfast and I MUCH prefered their old menu and so did the kids I was traveling with. The only reason you would get me back here is for a little girl who was very into princesses.
All in all you have to weigh out what you think is the best for your family. We have found that Minnie and Friends serves us nicely, but it's up to you!

Let us know what you end up doing though!

And... post pictures!!!
And above all... HAVE FUN!!!