So how do the rivals shape up?
In purely personal terms, the advantage must surely lie with our current Prime Minister. She does not carry the baggage - in terms of Collins' image as a "crusher", her communications with blogger Cameron Slater in Dirty Politics, her resignation as a minister over a visit to Oravida, a company her husband is linked with - that are inevitably part of the burden that the new National leader must carry.
Ardern has distinguished herself throughout her term as Prime Minister by virtue of her empathy, kindness and ability to unite and inspire us all in a great national campaign to defeat the coronavirus pandemic. So, in personal terms, advantage to Ardern.
But what about the policy front? It is here, surely, that Collins will seek to establish an advantage. As her predecessors, Simon Bridges and Muller both incessantly claimed, and indeed all National party leaders have always claimed, it is in managing the economy that National Governments come into their own.
And Winston Peters, worried no doubt about NZ First's poll ratings, has weighed in, claiming that National's nine-year stint in Government from 2008 to 2017 meant that NZ First alone had the necessary experience.
But how well do these claims stand up to proper examination? Would a new National Government, at this time of great economic risk, extend the legacy bequeathed to us by earlier National Governments?
That legacy included a run-down health service, with underpaid nursing and midwifery staff, rotting hospital buildings, and struggling GPs. It included under-funded schools and underpaid teachers. And it included the deterioration of our environment, so that we can no longer swim safely in our rivers or trust our drinking water.
And, in macro-economic terms, it has included perennial trade deficits and record levels of debt. It has included selling off state houses and allowing overseas interests to buy up some of our most valuable assets, and allowing others to blackmail us by demanding continuing subsidies as the price for keeping their businesses going.
"Managing the economy", under National Governments, in other words, has usually meant sacrificing everything for the sake of producing a surplus, even if that has meant running down our essential public services and abusing our public servants by failing to pay them properly.
So, the contest between Ardern and Collins may not quite follow the usually expected course. It may not be quite as simple as Ardern's personal qualities versus Collins' hard-headed approach to running the economy.
Collins will at least make a fight of it, but the balance of advantage may still weigh - in both personal and policy terms - in the Prime Minister's favour. Game on.
- Bryan Gould is an ex-British MP and former University of Waikato vice-chancellor.