I'll go against the grain. We've eaten as a family 3 times at both, and except for my wife, the rest of us much prefer the Sci-Fi. I can't imagine going a week at Disney without one of their burgers and milkshakes.
I'm of rather portly size and can eat my share, but I've never finished my meal at 50's. It's not the amount of food, it's how bad it's always been.
Both places are great experiences, though, and should be tried at least once.