We've been to both, although it's probably been 4 years since Cape May. They are both excellent breakfast buffets. As I remember Cape May, it was more laid back. The characters all came around to the tables, but there was no dancing or napkin waving like there is at Chef Mickey's. Chef Mickey's is louder and more frenzied, but a lot of fun.
We went to Cape May when our son was small and it was best for him as he is kind of quiet and reserved. Now that he is older, he loves Chef Mickey. Our daughter went to Chef Mickey at 9 months and loved it.
One thing to note, I don't remember Mickey at Cape May, only Minnie.
Have fun!