We've eaten at every TS In HS at least once. While it's not the most exciting meal (pretty inside and the portraits are neat, but no major wow), Brown Derby has been the best for food. Sometimes it's excellent, sometimes it's just good, but I've never left feeling disappointed. If you want to factor in atmosphere and experiences beyond food, Sci Fi is my choice. Mind you, I wouldn't stray beyond the burgers and shakes when dining there (I've been disappointed every time I have), but every burger I've had there has still been better than anything I've ever ordered at 50s. And while H&V can be fun for the characters, breakfast is the only decent meal we've had there, and I can't totally justify a place as a 'best' when characters are the best thing it has going for it. Mama Melrose was average to us (decent steaks for the cost, rest of the food was meh, and service was pleasant but slow)...only booked it because we wanted the Fantasmic pkg, were on DDP and didn't want to burn 2 credits. I don't really have any perspective on quick service since our main go-to place closed and snacks beyond the cupcakes and the old carrot cake cookie are all we've had.
We had a good dinner at 50s Prime Time in 2012 and, surprisingly, my husband and I really enjoyed the dinner during the Halloween seasonal dine in 2016 at Hollywood and Vine. However, none of them have been good enough for repeat visits. I would like to try Brown Derby once. Out of the 2 places we've eaten, my husband would chose 50s PT because he loves fried chicken. I would probably chose Hollywood and Vine because they had cocktail shrimp, garlic mashed potatoes, and lobster mac and cheese on the buffet 
