"better," as in the case where you have a larger than stock tire on a TJ and you prefer to move the tire away from the interior of the wheel well so as to reduce the likelihood of it rubbing at full lock on a CA or the Sway Bar.
3.75-4" is usually the range preferred.
EDIT: I do see now that the Quadratec Moab's you linked to have a 5" backspacing, which is stock. I wouldn't prefer it over a backspacing between 3.75-4".
I had no problem getting 31x10.50x15 "C" rated Duratracs for my XJ for my last month. Goodrich KO2s were also available in the same size. There were a few other brands but the list is definitely getting shorter.