Worst: For me, it would be a toss-Up between Pinocchio Haus and Toy Story Pizza Planet. If I'm going to pay those lovely park prices, I'd just as soon go somewhere and be given a seat (not fight for it!) and the food is more than a slab of mediocre pizza or a hot dog and fries (I guess I'm just not into WDW counter service, although I do love a good Turkey Leg or an egg roll in MK!)
For DH he would probably say his worst was Coral Reef. He didn't care for the menu -- he's more of a meat/potatoes kinda guy -- and felt it was very overpriced. Came away hungry but light in the wallet.
BEST: For me, that would probably be Whispering Canyon (for dinner). I love those sorts of antics, I love the WL theming, and the ribs I had were plentiful and excellent. DH had an EXCELLENT pork chop dinner, too. THe only thing we didn't like were the gnarly little corn cobs they served, but that's easy enough to set aside! We went there on a last second decision and all 5 of us were VERY pleased!
DH may have a different opinion, though -- seems like he ranked Chef Mickey's slightly above WC, although they may have been verrrry close. We had a really awesome meal at CM's -- the food was VERY fresh, good service, and tons of character attention. What's not to love?!?