Learning azir atm and I'm not sure whether I prefer double morello or morello+nashor's yet. The extra AS from nashor's is pretty nice, and I don't find I need the mana from morello, so it literally comes down to 20 AP verses 50 AS+620 more gold. My general impression so far is that nashor's is good if you can afford it, but morello makes for a good budget buy.
edit: I almost forgot the original topic, jeez. People ban free week champs they don't want to face all the time. Sometimes they even ban them because they don't want their teammates playing them (and subsequently sucking). Gnar and azir fit into both categories, where people don't want to fight a good one, but also can be difficult to use well, and thus don't want to risk one on their team either.