If you can only do one meal, then you'll have to prioritize which characters are more important to DD. At Tusker, you get Daisy, Mickey, Donald and Goofy, all are wearing safari clothing and hats. At Chef Mickey, you get Mickey, Minnie, Donald, Goofy and Pluto wearing chef's aprons and hats. You might want to show your DD some pictures of the characters and see which ones she likes better (we did both meals, see my oct trip report link for lots of pictures).
They both offer buffets and the food is pretty decent. Tusker's atmosphere has dark wood chairs/tables, with animal pictures on walls. The characters lead a parade every 15 minutes and pass out musical instruments. Chef Mickey's has a more lively feel with red/black/white colorings. Every 15 minutes they wave the napkins around and dance.
Both places are great, just need to prioritize the characters for your family. Have fun!!