I think Azir outclasses Cassiopeia

As a poker, as a lategame carry and in teamfight utility.

Poke: Azir's Q+AA> Cassio's Q Mobility: Azir's E> Cassio's Q (MS when hit, meanwhile Ahri always gets it even if she misses her Q.) Damage: Azir's soldiers deal aoe constant damage, Cass has better single target dps, but she has to get very close with no scape while Azir can keep at a safer distance and can peel with ult or E. Utility: Azir's ult is way better than Cass's, only time Cass's is better is when you land a lucky flash+ult. It has short range and can get counterplayed by turning around, even kalista can just keep looking forward while hopping backwards and she won't get stunned (logic...)

So yeah, I know they both have their cons and pros, but I think Cassiopeia really falls out of flavor when compared to other ap scaling mages like Azir or Viktor. Just my thoughts.