Reasons for support

In the spirit of inclusiveness promoted above, here's some positive reasons to vote for each of the different components of the left.

Five reasons to vote Labour

• Employment issues: Labour's achievements here are excellent (lowest unemployment in the OECD, anyone?), but I think two really stand out: they've restored the power of unions, so workers can actually fight for and win wage gains (see the success of the fair share campaign), and they've raised the minimum wage substantially, from $7/hour to $9.50 /hour. Both of these have delivered real gains, and helped ensure that the fruits of growth are distributed more widely than they were under previous governments.
• The Civil Union Act: It's not full gay marriage, but it is still a progressive step. And while there were traitors in the ranks, Labour stood by its ideals and pushed it through at no small political cost to itself.
• KiwiSaver: not implemented yet, but stands to enable people to pursue the kiwi dream of owning their own home. A solid, social democratic policy.
• Zero-interest student loans: a seisachtheia for students and graduates, which makes those "loans" actually repayable.
• To boost their chances of being the largest party on the night, and thus of getting Winston's support (for whatever that's worth).

Five reasons to vote Green

• Human rights: the Green party have been Parliament's most consistent and eloquent defenders of human rights. They stood up for Ahmed Zaoui and the right of everyone to a fair trial. They've opposed government legislation such as the Identities Bill, and the Terrorism Suppression Amendment Bill, which erodes the rule of law by allowing the government to criminalise behaviour ex post facto. They took a firm stand for a secular and liberal society over civil unions. And they've been a conscience on foreign policy, speaking out where the government has remained silent.
• Energy policy: they've been wonking away for years in this area, and the result is a reasonable and sensible path to a sustainable future - so much so that Labour have flogged most of their ideas.
• The environment: does it really need to be said? We have an image of being "clean and green", but this is due to not having very many people, and not really borne out by the reality. Just look at our lakes and rivers, for example. Air quality in our cities isn't that hot either. Then there's our forests and our native birds. While most of our political parties have some tinge of Green, it is the Greens' core value.
• Social justice: on social policy, employment law, housing, the Greens stand for a society where everyone is taken care of, where no-one goes hungry, and where everyone has equal access to opportunities. And they stand for using the power of the state to fight inequality and discrimination. This accord well with the left's core values of substantive freedom and equality.
• Because a left-wing government will not be possible if the Greens just miss the threshold.

Two reasons to vote Progressive (because they're small)

• Matt Robson: he has been a consistent critic of the government on human rights issues, and a conscientious defender of liberal values. He's stood up for Ahmed Zaoui and the Iraqi immigrants Winston smeared; he's opposed the Prisoners' and Victims' Claims Bill, the Identities Bill, and numerous other pieces of legislation that eroded fundamental human rights. It's such a shame he had to ruin it by trying to raise the drinking age.
• Economic development: the Progressives are all about building a higher-wage economy through innovation and improving productivity. Again, this will ensure that the fruits of growth are more evenly distributed. But more importantly, it also represents a distinctive response to globalisation. Rather than opposing free trade, they're trying to mollify its effects and work out how we can live with it, in the same way that Labour is working out how we can live with a market economy. If you're an internationalist with some qualms about free trade, this is an interesting project, and one that seems worth pursuing.

Which party you find most compelling will obviously depend on your particular values, but IMHO there are good reasons to vote for all of them.