Button first. Reduces stress on the zipper. Nobody wants premature zipper failure.

button first, both closing and opening.

Button first. Makes it easier to zip.

Button -> Zipper

I leave them both open for ventilation.

Tuck in undershirt, button, buckle belt. Do things for a couple hours. Wife tells me my pants are unzipped again

I usually button the button and immediately forget to zip the fly. Hours later after I've been in public all day I'll notice that the fly is unzipped and try to zip it without anyone noticing.

Button first, then zipper, then put on pants.

Zip, then button

Button first, zipper if I can be bothered ¯⁠\⁠_⁠(⁠ツ⁠)⁠_⁠/⁠¯

Was someone watching the first season of Babylon 5?

Button then zip

Button, then forget to zip until there's a cold breeze

Button first then forget to zip

Zipper then button. Button first feels weird to me

If they are loose enough sometimes I do the zipper first, otherwise I do the button first to make the zipping easier.

https://youtu.be/TlZXxwsmLdE?t=19

Zipper.

Wow. I am in the minority here, but zipper first! Hold the button and button hole together in one hand, zip up, and then button! Always!

Depends how tight my pants are

That's a good question for which I don't know the answer, even though I do it quite often. 🤯

Vinage 501s so I button my button first then button my zipper.