I think you need to experience both of these restaurants~they are so different. If you can only do one, then you have to ask yourself this. Do you want some theatrics in your dining experience or would you rather just kick back and enjoy the show. If you like a little bit of a show w/your dining, then for for the 50's prime time. My family got a kick out of it, but some would probably rather be left alone.
The food is decent at both places~but the Sci-Fi is more of a sandwich kinda place.