Combined one of the section headings in the text, which basically gives away the conclusion, with the caveat that it's about undamaged QR codes. As you can expect more damage (such as when tattooing one, or paper that goes around), higher error correction does make sense; same when overlaying graphics/logos.

I found this surprising. I'll be displaying QR codes on a screen, so for me L easily makes the most sense in order to be able to make it larger with fewer squares inside of it.