On paper Auburn may be a better job (more $$$, more fan support, easier to recruit), but it's well known that the inmates (big donors) run the prison there, and it's a win now or get out environment...that's on top of having to coach in Saban's shadow and coach in the toughest division in college football. Donors ran off the AD this year, and were actively trying to get rid of Harsin DURING the season last year.
Some coaches will embrace it, other coaches will look elsewhere. Auburn is one of those "good from afar, but far from good" situations.