Changes to regulations ahead of the 2014 season, which mandated the use of turbo-hybrid engines, contributed to the start of a highly successful era for Hamilton as he found himself in the most dominant car on the grid. That year saw Mercedes win 16 of the 19 races that season, 11 of those secured by Hamilton as he prevailed in a season-long duel for the title against teammate Rosberg. Clinching his second drivers' title, and eclipsing the victory tally of all British drivers before him, Hamilton declared over team-radio after the final race in Abu Dhabi, "This is the greatest day of my life". New driver number regulations brought in for 2014 allowed drivers to pick a unique car number to use for their entire career, and so Hamilton elected to drive under his old karting number, 44, for the remainder of his career.
After Hamilton clinched his second and third World Championship titles with Mercedes in 2014 and 2015, David Coulthard declared Hamilton the best driver of his generation, calling him "the Ayrton Senna of his era", an opinion which was more widely accepted amongst the public, experts, and fellow and former drivers. As Hamilton became more widely considered the best driver of his era, public and expert debate moved from his status in modern Formula One to his status amongst the greatest drivers in history. The next few seasons saw Hamilton eclipse a number of records, including achieving the most all-time pole positions ahead of Michael Schumacher, leading him to be regarded by some as the greatest qualifier in history. After winning his fourth and fifth world titles, Hamilton's place among the greats of the sport became firmly established in the opinions of experts, rivals and teammates alike, with some journalists and pundits considering the possibility of Hamilton being the greatest Formula One driver of all time. Following Hamilton clinching a sixth World Drivers' Championship title in 2019, ex-Formula One driver and pundit Johnny Herbert acclaimed Hamilton as the greatest driver ever, a sentiment echoed by his Mercedes team-boss Toto Wolff, who described him as "maybe the best driver that has ever existed", while Formula One staff writer, Greg Stuart, described Hamilton as "arguably the most complete Formula [One] driver ever".
From a young age, Hamilton's helmet throughout his karting years was predominantly yellow with blue, green and red ribbons. In later years a white ring was added and the ribbons were moved forward to make room for logos and advertisement space. Hamilton continued to run a predominantly yellow design for the early stage of his Formula One career, but in 2014 decided to change to a mostly white approach. In 2017, Hamilton selected his helmet design from fan submissions. The winning design used a white and yellow base colour with red and orange details, and the addition of three stars – one for each of Hamilton's three Formula One championships at that time – on either side. Over the following seasons, Hamilton continued to add more stars to his helmet upon winning further World Championship titles.
Hamilton's treatment by the media and critics has, at times, been criticised as being racist. In 2014, The Guardian journalist Joseph Harker highlighted double-standards in Hamilton's treatment compared to other British drivers by British newspapers, suggesting that his skin colour has played a factor in a perceived lack of acceptance amongst the British public. In 2019, footballer Rio Ferdinand described media scrutiny of Hamilton as having "racist undertones" and contrasted Hamilton's treatment to that of fellow British driver Jenson Button. At the start of his Formula One career, Hamilton said that he "tried to ignore the fact [he] was the first black guy ever to race in the sport" but later stated that he had since grown to "appreciate the implications", and changed his approach to embrace his position and promote equality within the sport. Hamilton has since questioned racial politics in Formula One on a number of occasions. In 2011, after being summoned to the stewards in five out of the first six races of the season, Hamilton quipped: "Maybe it's because I'm black, that's what Ali G says". In 2018, Hamilton criticised the lack of diversity in Formula One, describing how nothing had changed in his eleven years in the sport before saying "Kids, people, there are so many jobs in this sport of which anybody, no matter your ethnicity or background, can make it and fit in". In 2019, Toto Wolff, Hamilton's team boss at Mercedes, described how Hamilton was "scarred for life" by racist abuse inflicted during his childhood.