With Lee's death at age 91, Mahathir becomes the last of the old-guard generation in Southeast Asia, which boomed economically under their authoritarian leadership and came to be known as the "tiger economies" (Indonesia's Suharto, spoken in the same breath as these two, died in 2008).

Yet Mahathir and Lee leave vastly differing legacies.

To his last breath, Lee was a commanding presence in Singaporean politics and the region, despite having stepped down as prime minister in 1990. He also successfully groomed his son Lee Hsien Loong, who became Singapore's prime minister in 2004.

Mahathir, however, failed to retain the same clout and esteem after stepping down in 2003.

Today he is seen by many as an inveterate meddler, who rails against the failings of his successors and bemoans in his blog the weak governance of a country he once dominated.

Just this past week he launched a stinging attack - his harshest yet - on beleaguered Prime Minister Najib Razak, warning that the dominant United Malays National Organisation would lose power with Najib at the helm of the party Mahathir once headed. He said Malaysians "no longer trust" Najib.

"UMNO members and their leaders must realise that [the government] will lose if [Najib] leads UMNO," into the next elections, due by 2018, he wrote.

"It is not easy for me to write this blog post. But for the sake of the [Malay] race and the country I have to expose all of this."

His broadside alluded to a key difference in the policies fostered by Malaysia and Singapore; while Lee emphasised a meritocracy that was scrupulously inclusive of all ethnicities, Malaysia has pressed on with Mahathir's system of favouritism towards Malays that fosters intense disgruntlement among minority Chinese and Indians.

During his 31 years as prime minister, Lee transformed Singapore, a marshy island trading post with no natural resources, into Asia's richest nation as measured by GDP per capita, five times higher than Malaysia. He crushed corruption at all levels, built a top-notch, efficient bureaucracy, set up an excellent education system and focused on creating world-class service industries that would be competitive in a global market.

Mahathir, meanwhile, pushed a patronage system by giving out contracts to his cronies, and his policies increased bureaucratic red tape. Despite having far more resources and a much bigger workforce, he promoted and protected inefficient industries such as steel and cars with tariff protection.

Both men ruled with an iron fist. Lee faced criticism for the strict limits on free speech and public protest, which he insisted were necessary to maintain stability and order and to promote economic growth in his multi-ethnic, multi-religious country. Mahathir used a security law allowing indefinite detention without trial against political opponents and critics.

Malaysian political analyst Ibrahim Suffian says: "Both men are equally Machiavellian in their methods. They are both alike in the kind of politics they employ but Lee Kuan Yew achieved much, much more than Mahathir despite having a lot less resources and capital."

Mahathir, a doctor-turned-politician and Malaysia's fourth prime minister, nevertheless helped turn the country from an agricultural backwater into a key trading nation during his 22-year rule.

With the help of massive petroleum and palm oil revenues, he oversaw grand infrastructure projects such as the Petronas Twin Towers, which were once the world's tallest; he also built a technology hub, a new capital city and a Formula 1 race track.

Yet Singapore's higher wages, standard of living and merit-based system have been a benchmark for the region - and have drawn tens of thousands of Malaysians, mainly ethnic Chinese, to the city state.

A 2011 World Bank report said more than one million Malaysians live abroad and warned the outflow of skilled workers could hurt Malaysia's economy.

Although the two were contemporaries Lee shot to prominence much earlier. He was already the prime minister of Singapore when it became independent of British colonial rule in 1963. The same year the small island-nation joined neighbouring Malaya to form the Federation of Malaysia, believing it needed to be part of a bigger country to survive. Mahathir became a member of parliament in 1964, and that was the first time the two met.

"We crossed swords many times during the debates. But there was no enmity, only differences in our views of what was good for the newborn nation," Mahathir wrote.

But the federation was a marriage that was doomed to fail. For one, the ethnic Malay leaders of Malaysia were suspicious of ethnic Chinese Lee. Ideological and political differences soon surfaced, and Singapore was expelled from the federation in 1965, leaving Lee to set his own course with a vision that still defines Singapore.

He ensured that the country ran on meritocracy. He demanded the best prices and most efficient companies handle government projects. Government-linked companies compete for projects with private companies.

"Despite his autocracy, Lee Kuan Yew was driven with building meritocracy that saw Singapore grow by leaps and bounds, but Malaysia is hobbled by its racial politics and insecurities," Ibrahim says.

Mahathir, who became prime minister in 1981, championed an affirmative action programme for the country's Malay majority. Mahathir saw the Malays - with good reason - as downtrodden and gave them privileges in business, education and housing.

He promoted race-based politics to ensure that his Malay party dominated politics. For better or worse, that legacy continues today.