Brown Derby is amazing. It's also so far ahead of the typical WDW crowd (you know, the people who find Be Our Guest's menu "too fancy" and never drink Starbucks) that I can see why it's largely ignored/forgotten.
50s Prime Time is decent food in an atmosphere that can be anywhere from interesting to flat-out Adventurers Club-level hilarious, depending on your server.
Only been to SciFi once in the past couple years, but I remember an above average burger, very good server. I know the place gets savaged online, maybe I just got lucky. The atmosphere is a lot of fun.
Backlot Express is probably the best QSR on property not named "Earl of Sandwich." I enjoy the outdoor food court on Sunset as well (mac & cheese dog!). Starring Rolls beats the Main St. Bakery, IMO, other than in its limited hours.
On the flip side, ABC Commissary is the worst QSR on property. Pizza Planet is nasty, a close second for worst QSR. Studio Catering Co. is average at best.
Overall, room for improvement in QS but not the worst park in Orlando by any stretch.