It depends on the cat. I have two. One that if given the option to free feed will eat herself sick. The other does just fine. So we went to automated feeders 4 times a day to control what she gets. The upside is that we can go out of town and not have someone take over the feeding. (We have someone come in to check on them, brush them, love them and steal poo from their box.)
I'm feeding them Nutrisca Chicken Cat Food, because it has a low glycemic index and doesn't have corn as the first ingredient. (I'd be interested in other options.)