They are both icons. Lombardi owned the 1960s. Belichick has owned the 2000s.
I will give you this, though ... as much as I respect Bill Walsh and what he did to change the game in the 1980s ... what Belichick has done in New England is clearly superior to what occurred in San Fran in those days.
The 49ers got fat in the NFL's wild, wild west era when any team could spend as much as it wanted ... and everybody knew that Easy Ed was doing some serious book-cooking to make sure the San Francisco rosters were loaded, year in and year out.
Not so during Billy Burger's time in New England.