While I know we all hate the Pittsburg Steelers with passion, I would honestly say, for the sake of our division, rooting for them is the best option.
Yes, we're reduced to rooting for our most-loathed team in the NFL (that's how much we're reduced to in this shitty season), but it remains clear: NFL teams that win the Superbowl often do very well in the following seasons and make it into the post-season. On the other hand, teams that lose the Superbowl often do not make it into the post-season and/or drop out of the 'elite' status the team once was. There are statistics that back this up (though, I can't find it at the moment). And, yes, I guess the Seahawks were sort of an exception.
That being said, I'd rather have the Cardinals lose and have a downward spiral that helps us get back to being the divisional champs.