I’ve only bought one phone new retail, the rest have been used from eBay for my partner and I. I’ll typically go with a reseller (they typically have better prices and Buy It Now, instead of individuals who still like the auctions).
I like to support reusing items as a matter of course and am willing to skip out on the unboxing fun, like peeling the stickers off, etc. I don’t recall any issue I’ve had that wasn’t resolved quickly by the seller.