Zero; paid it off early with no regrets.
So you pay no insurance no taxes and do no maintenance. Where do you love I'd like to move to a place none of these were needed
You must have an interesting definition of "mortgage" that includes taxes and maintenance. Mine doesn't.
To be equal to rent, wouldn't it make sense to include those numbers in your mortgage? REnt implicitly covers your share of those expenses.
Not to me, because that varies from one situation to the next. Some rent agreements cover pretty much everything that can go wrong with a property, maintenance-wise, while others will cover next to nothing. Besides that, the decision of whether to rent or own is up to the individual, as is the decision to live in a HCOL area vs a LCOL one, or a larger property vs a smaller one, or a rented property with many / all utilities vs one with few / none included.
Too many assumptions to take into account once we start going above and beyond the OP's question. I'd rather just answer what the OP directly asked, which was the percentage of income spent on rent or a mortgage. S/he even clarified further that s/he was only referring to monthly required payments by asking people specifically not to make calculations based on pre-payments.
And to answer the rest of the OP's question, before paying it off, it varied, because we started making more income over time. By the time we paid it off, our annual income was more than the cost of our home, so I voted under 10%.