I would choose MM because my DD cried when we went to Sci-fi. She hated the movie trailers and even when we turned her away from them she begged to leave. DD is now 11 and it is the running joke because she will not go to the restaurant now.
Take a look at the menus at the top of the page under the dining tab. One is a family Italian sort of place. The other is burgers/salad. Are you deciding based on the food or the atmosphere? You know your own kids preferences best.
Sci Fi- we enjoy both but sci fi will appeal much , much more. Big drive in movie screen, silly old movies, sitting in cars,,kids(and adults always enjoy the atmosphere.