Personally I was disappointed in the food in Schi-Fi, thought the food there was tasteless. On the other side, sitting in a huge indoor drive in was pretty cool. I'm a big fan of Hollywood and Vine though, I never go to DHS without eating there. Even as an adult I'm a sucker for those BBQ meatballs in the kiddie section of the buffet Doesn't hurt that there's a desert buffet included either
Totally depends on whether you prefer a buffet or table service (a la carte). I have NEVER had a decent meal at H&V (check out the dining reviews) but YMMV. On the other hand, Sci Fi serves a decent meal (check out the menus) and has great atmosphere.
My vote is for hollywood and vine, I like the buffet and all you can eat, The sci-fi is really kind of dark and noisey inside like going to an outdoor drive in, you may not be able to do much talking there.
H&V was hands down the worst table service meal we have ever had in all of our many visits. We always enjoy Sci Fi, I have it booked twice for lunch next week.
I vote Sci Fi. We have a 4 and 1 and 1/2 year old boys. They really enjoyed sitting in the cars. We love the atmosphere there and the super yummy milkshakes.