My vote would be the omlettes at Brian's Restaurant in Lapeer, Michigan.
I made that a regular morning stop when I lived in the area. Would almost
get in my car and drive the six hours for one now.
Second place was the omlette bar at a Radisson Hotel I stayed at in Nashville.
For a chain food offering, the Meat Lover's Omelette at Friendly's ain't half-bad
(https://www.friendlys.com/wp-content/themes/netplus/img/production/detail/menu/breakfast_omelettes_meat-lovers-omelette.jpg)