A great D is always more impressive for me to watch. IF you care, here is why:
Watching the defenses of the Rams (75-78), Bears (85-87), Steelers (pick a year) or the Seahawks (2013) is more impressive than watching the offenses that are great Rams (99-2001), Broncos (2013), Washington (83), because:
Many times, it seems like some offenses 'trick' the defense, or the defense has fear of their speed...but a great D never tricks, it dominates. When teams stopped fearing the Rams speed, they played them better (Tampa & Giants 2001.
I think the Rams offense (99-2001) had a few games where the defenses just smashed them, and the
Rams didn't look so good. A great D never allows that happen (IN GENERAL)