The question at MGM is more like "which is the least bad counter service?" None of the CSs there are very good, IMO, but Backlot is not terrible. ABC Commisary *is* terrible. I haven't tried the new Studio Catering Co. yet - maybe it's an improvement.
On the other hand, table service at MGM is really good - I'm fond of all 5 TS restaurants there (Sci Fi, 50's Prime Time, Mama Melrose, Hollywood & Vine, and the Brown Derby). It's so interesting to me how that park can get the TS so right and the CS so wrong!