I have bespoke with button flys having been caught up in the romance of the extra handwork , that they are distinctive, etc., and then end up wishing I had ordered zippers. My last suit and pants order had zippers.
I bought some RTW tweed pants with button flies, and they are a pain to re-button. Go with the zipper. I remember asking my tailor what his views were when I started patronizing him and he said, without hesitation, that zippers are better. As usual, he was right.