I'm a yyyy-mm-dd kind of person. Makes sorting filenames and folders easier.
Hate when I paste a table into excel and the date formats are not the same.
I hate it when I want "Jan-22" in Excel and it assumes I want "2/1/22". I use mmm-YY a TON in the big project I'm currently working on and when Excel thinks it's smarter than me, we have problems.