Physical sticker exposed to the environment. Scrapes/marks are common, they would render the “HR” code useless, but the QR would be fine. Or at least stay fine for longer. So the trade off becomes: do I post something that will be accessible to everyone, even those without a phone, for a week; or do I post something that will be accessible to everyone with a phone for two weeks. Given almost everyone has a phone, the answer is obvious. (Making up the times, but you get the idea)
A lot of applications centralize their logo in a QR code, obscuring a significant chunk. Yet the code scans fine and there is some nice custom recognizability for which service it is.