Comfortable black flats suggestions needed

I am looking for relatively plain black flats (no bows, metal, etc.) My feet are a little strange so they can be hard to find.
The most important thing is comfort and I’m willing to spend more if they will work for me.
Some I’m considering:
Allbirds Tree Breezers
Vivaia Square Toe Mary Jane

I generally wouldn’t have considered a Mary Jane but maybe they’ll be more comfortable for a lot of walking and fit better

Please share suggestions and let me know if they seem to fit true to size or if I should go up or down in size.