One household, one vote.
Married people raising their own genetic offspring are consistently the people who have the most stake in making sure society is set up for the future, as opposed to instant gratification—i.e. degeneracy, consoomerism, and government handouts.
My logic is based on the ground that the family, and indirectly then marriage, is the building block of society. Single people really aren’t a part of that building block in a meaningful way. They may be useful contributors to society, but they’re not nearly as important, in general, as the family unit.
Married people DO vote differently than non-married. Look it up.
No question that you can be unmarried or single and still want the best for future generations, but it's not as sure of a thing. Whenever you see someone pushing for insane, unsustainable, or wicked policies, they are almost universally single. That is the norm. Well-meaning and low time preference singles are the exception, and you shouldn't set up your society based on exceptions. This is true even if I don’t like the results of the voting, and even if this system disqualifies me myself from voting, but at least it's honest in what it's selecting for.
One household, one vote.