Stomach definately. I'll tickle feet if they're extremely ticklish and stuff, but I think feet are kinda ick so they have to be pretty ticklish, or he most ticklish spot on a irl to get me to tickle them.
I love my feet tickled of course, romantically, and it makes me laugh, squirm and moan.. alot. At the same time, I love to tickle a guy on his sides, or even his feet if i can reach them while we're in bed. But yes, it's my feet that make me react most.
As for me when I ler I'll go for whatever I get access too. But I tend to hold feet for last considering how it can be one of the most ticklish spots. Build up the suspence