This is a good topic. I think there's a quality of muscle that needs bigger legs to balance it out. I was gonna site Levrone as an example, as his legs were awesome the first few years of his career, but near the end, he looked good then with smaller legs. I don't know, but this is a good topic. Sometimes huge legs make guys look like roid apes. Branch Warren, Paul Demayo, Mike Morris, everyone with the craziest legs have had a sort of look that implied functional incompetence. Levrone still didn't have that look, but you wouldn't have wanted to see Mike Francois with legs any less than what his were in his prime, either. Porter Cottrel's weren't overpowering, but they weren't considered anything like Arnold or Zane's, either. That guy that Arvilla posted the pictures of this morning had those sick, shredded meat-looking legs, too...probably not an asthetic ideal...the word "aesthetic" doesn't come to mind when looking at them, but guys with that mega-dosage look can be considered symmetrical. Maybe it has something to do with muscle belly appearance in the upper body. The longer bellies, like Arnold's biceps, and really low-inserting lats and drooping traps need longer-looking legs. Vince Taylor had sick (good) quads...they didn't make him look non-functional, though.
Shit, this is really hard to put your finger on. Maybe the best look for someone is the one that reflects their current persona/soul/being/mindset/who they are, etc.