If we are talking Theme Park food by itself, I'd like to know of another park that offers a wider selection & better quality then the parks at WDW. We can even exclude Epcot because of the unfair advantage it has over other parks.
A "must do" dining experience every trip is the Flame Tree BBQ. If you want to call their slab of St Louis Ribs "common" or "average" you're crazy. FT BBQ serves excellent food - even their baked beans are great.
MGM: Hard to call Brown Derby, Hollywood & Vine, Prime Time Cafe or Mama Melrose's "average park fare".
MK: Tony's, Crystal Palace, Cindy's, etc...... Average ???
If all else fails, grab a turkey leg and knawl away. Where could you possibly find a better tasting turkey leg ?