I've only "heard stories" about Balmung and Gilgamesh (one being full of gooners and the other having rampant toxicity), but it's hard to say if its actually the locals that give it those reputations, or if its visitors bringing and reinforcing the stereotypes.

I know from living on them that there was nothing particularly noteworthy about Maduin and Excalibur, I couldn't even tell you if any "famous" players or FCs existed on them.