For used/second hand I don't care unless it ties to longer term quality or fit.

For 1 example, used Levi's are really easy to shop for because of numerical fit/shape codes on the back tag.

For new, I have to take into account who's getting my money so brand and everything tied into that brand is number 1. Ownership, business, ethics are all under that brand umbrella.

I tend to avoid buying new if possible. Makes it easier to just pick what I want.