We just ate at both last week and loved both. CM has more variety. If your child doesn't like the platter they have at Garden Grill, they will bring them their own platter with mac&cheese, chicken nuggets and french fries. DD liked both desserts (build a sundae at CM or decorate a cupcake at GG). We will return to both. Good luck deciding!
I prefer Chef Mickey's over Garden Grill by far. The Garden Grill had food that was bland and had no flavor. Mickey was not into character. Service and the other characters were good though.
Chef Mickey's was the best. All the characters were amazing and came over several times. We had a late ADR (around 9pm for dinner) and since the restaurant was almost empty, we were even able to get a group pic of my family with Goofy, Minnie and Pluto all together!!! Food was great but I just wish they had a larger variety. Service pretty good too!