This is based on just one trip, and we didn't get to try nearly as much as we would have liked(who does, though?), and we didn't try a buffet during that trip. But...
What is the Best Disney Quick-Service Restaurant? Katsura Grill in WS. I've raved about it being a great spot for watching the lights come on after sunset before, but the food was excellent. My wife talked me into trying udon noodles, and it's now a regular thing back home.
What is the Best Disney Table-Service Restaurant? The Wave. I agree this is a real hidden gem, from the atmosphere and service to the food and drinks, I just can't say enough good things about this place. The swordfish is incredible, and for some reason I kept raving about the croutons that came with the dish. If you haven't tried it, it's worth the trip. Plus it's all sustainable and pretty healthy to boot. This is going to be our regular special place for our trips down.