For several years, my family did the "Best Burger in the World" reviews on rec.arts.disney.parks newsgroup. You might be able to find some on some of trip-report sites or on Google groups archives.
Our favorite burger was at Evergreens, the restaurant in the now-military only Shades of Green; that was before their renovation, so we don't know how they are now. Other excellent burgers were at Concourse Steakhouse (where the service was excellent, btw, and you often won't go wrong with a burger at a steakhouse), Sandtrap at Eagle Golf Course, Whispering Canyon, and (off-site) at Jungle Jim's at the Crossroads Shopping Center. Our worst burgers were at Krystal (yes, we tried LOTS of places). Unlike an earlier poster, we had an AWFUL burger at Beaches & Cream; in fact, twice we had bad experiences there, including melted ice cream, undercooked food, and a hot dog which had literally spoiled before being cooked. Once we had a good experience at B&C, but not on a par with some of the other opportunities available. YMMV.
Even with the new style of providing toppings for the burgers, the in-park burgers are not the best. Better to use your mid-day break to find one of the truly wonderful burgers available at the resort hotels or nearby restaurants.
Loved the pictures, though! Note that our burger grading scale included presentation, bun (toasted, firmness, taste, freshness), toppings and garnishes, texture and taste of the meat, and service. Except for the last, you can get a good idea from Toyman70's wonderful pictures.
We are going to reprise our survey in a few weeks, hoping to add a couple of the new places as well.