Maybe great disagreement comes but ...
I think a great restaurant is not related to how expensive, how great deco or good service but somehow an emotional effect...
My vote goes to not a restaurant but an on street stall. I never forget the following senario when I was a child:

With my mother walking on the Street (in Sau Kei Wan, Hong Kong Island, HKG, if you know) in Winter (1x degree C), walking for an hour carrying stuff for a temple visit. We walked pass a stall selling Wonton/Fishball Noodles, my mum said that it was there since she was a child (she lived 1 block from the stall until age 1x). No indoor seating, we sat on the table and chairs on the street and had (less than US$2 per bowl) noodles. The noodle was hot, especially when winter winds blow against you. I asking my mum what the street look late some 30-40 years ago, she "enjoying" the flash-back of momoey of the old ages...

Great feeling, great food, WARMEST human sensation.

(Sorry for long story and off-track but I think even the most expensive restaurant I tried in can't beat this "cheap" stall.)