If you want a tasty proper burger LTN Phobia you order them at the classic steakhouses in NYC/Chicago etc.
And then you have specialised joints such as Shake Shack (very good burgers), Burger Joint at Parker Meridien NYC, and many other good places in NY.

Burger and Lobster in London also does pretty good burgers. There is one in Mayfair just of Piccadilly.