Another vote for Garden Grill. We have three boys, ages 5, 12 and 13 and we've been taking kids to Disney since our oldest was a year old. We've been to both Chef Mickey's and Garden Grill multiple times. Garden Grill is our family's favorite character meal in all of WDW for the reasons others mentioned: great character interaction, far more relaxed setting than any other character meal, fresh food that they bring directly to your table, etc.
Even if you have another adult to sit with your children while you juggle buffet plates, we think it's far easier to just sit with our kids, let the food come to us, visit with each other and meet the characters. The high booths on the lower level also keep little ones focused on food for just a few minutes because they don't see the characters walking around until they arrive at your table. Our kids always get a few bites in at Garden Grill! As our kids get older, we've significantly decreased our character dining at WDW, but Garden Grill is the last character meal standing for so many reasons.