After months of campaigning, it's time for Londoners to make up their minds about which Mayor will run our city in the next four crucial years.
This is the time to look back on the records of both men: what each inherited, and their legacies.
For Labour you have an effective and uniquely experienced 'executive' Mayor, with an encyclopaedic knowledge of London - Ken Livingstone
For the Tories a convivial part-time 'ceremonial' Mayor, good at opening things, one-liners and endless waffle - Boris Johnson.
Compare their records.
When Ken was elected in 2000 London was a world city at risk after 14 years with no citywide government.
The transport system was creaking at the seams: internationally, London was renowned for being easy to get to but difficult to get around, with congested streets and ramshackle public transport. There was an acute housing crisis, growing inequalities and a huge backlog of investment in social infrastructure and the environment.
As London's first elected Mayor, Ken set up the GLA from scratch, defining its modus operandi and establishing its vision and goals. As his Deputy Mayor I was part of that process, and honestly cannot imagine anyone who could have got the authority up and running more efficiently or more quickly than Ken. While being happy to debate and discuss issues with staff, stakeholders and the public, Ken had a complete grasp of the options and admirable decisiveness.
He was acutely aware that the new authority had to tackle lots of things at once.
He began a revolution in how we police our city. He increased the number of police on the streets, bringing them out of their cars and into our communities, introducing the Safer Neighbourhoods community policing teams in every ward in London.
He tackled the then woefully inadequate transport system. In the short term, he massively improved the bus system, adding a third to the fleet and draconian enforcement of bus lanes.
At the same time he began a rail renaissance - tube modernisation; creating the overground network, including the East London Line extension; and getting Crossrail agreed and funded after decades of procrastination by central governments. Ken also prepared a programme of future transport projects post 2018 and, of course, introduced the Oyster Card, congestion charge and the London Low Emission Zone. These and other policies resulted in the fastest shift out of the private car and onto bikes, buses, and feet in any major city in the world.
He inherited a housing crisis and a rapidly rising population. He doubled the number of homes built in London each year from 17,000 to 32,000 and worked towards 50% affordable homes in every housing development. He secured from the Labour government the largest housing investment budget ever in London - £5bn over to provide 50,000 homes in three years.
He tackled London's huge carbon footprint with a raft of measures including the first comprehensive Climate Change Action Plan and set up the C40 group of large cities worldwide to collaborate to address climate change at the metropolitan scale.
He took on the challenge of regenerating the Thames Gateway, the largest concentration of multiply deprived communities in Western Europe. It was Ken who spearheaded the campaign to secure the Olympic and Paralympic Games for London to give momentum to the regeneration of East London and the Thames Gateway.
In short, Ken gave us a powerful vision for the future - "to develop London as an exemplary sustainable world city" - and provided the means to deliver it.
He also introduced a raft of policies to make London a fairer and more equal city. He created the women's unit at city hall, provided assistance with child care, gave under 18s free travel and funded a host of events celebrating the many cultures across London.
Boris Johnson inherited that catalogue of solid achievements when he entered City Hall in 2008 and has spent the past four years enjoying the fruits of Ken's labour. From Crossrail to the Olympics, Johnson has merely cut the ribbons on Ken's projects.
Johnson has done very little, but he's undone a great deal.
His first act was to cancel nearly all of Ken's long-term transport projects, starting with the Thames Gateway Bridge.
He weakened the London Plan, especially in respect of housing, abandoning Ken's ambitious target that 50 percent of all new homes should be affordable.
He squandered the record £5 billion housing budget, failing to deliver the 50,000 affordable homes by 2011.
He got rid of the accessible bendy buses and replaced them with eight 'Boris Buses' at about £1.25 m each... probably the most expensive bus in the world!
Despite his claims to the contrary, he managed to reduce by almost 2,000 the number of police officers in advance of the Olympics and Paralympics.
And when his leadership was tested last summer, during the August Riots, he utterly failed even the basic test of being in London. What a contrast to Ken's response to 7/7.
Perhaps most serious of all, while Ken is campaigning against the Tory government's welfare reforms, Boris Johnson 'absolutely' supports them. By 2016 only 20% of inner-London and less than half of outer-London neighbourhoods will be affordable to people receiving housing benefit - most of who are either in work or pensioners.
As we are starting to see, this will change the social fabric of London. It will create social segregation on an unprecedented scale and undo the mixed communities that have driven London's social and economic success.
As a Tory Mayor, Boris has been obsessed with the Tory agenda. This is the man who in September 2010 said:
"You know we in the government in London have been making very substantial cuts for the last two years. I don't think there's any part of government across Whitehall that's moved so far and so fast to make cuts."
The fact is that even before the recession Boris's main activity as a part-time Mayor has been cutting investment in London.
That is why there is virtually nothing for him to call his own and nothing in the locker for the next term. As a cabbie put it to me, we got a bunch of bikes for city blokes, when we could have had a bridge over the Thames for east enders.
In contrast, Ken's record shows he will fight to make London a fairer and more equal city. He will deliver more homes that Londoners can afford, safer streets, more jobs and training and better transport with cheaper tube and bus fares.
He has new ideas about delivering more affordable homes in partnership with the pension funds and a serious commitment to cutting London's carbon emissions.
Ken has the record the show that he'll deliver for all Londoners and that he speaks for all Londoners in a crisis.
In the end, the sensible choice is Ken.
The only arguments against him have been a relentless stream of negative campaigning. That worked in 2008. Don't let Boris get away with it again.
Follow Nicky Gavron on Twitter: www.twitter.com/nickygavron