Depends on float height, obviously.
Whiffing a full jump aerial can be very awful in that matchup though, because if she gets beneath you and you don't have an easy escape route you'll eat aerials or she'll just park herself in your landing space and wait to d-smash you. And DoH knows how to kill Nana very well so even a small error like "choosing to full jump at the wrong time" could cost you massive momentum and potential for he entire stock.
There's a lot of factors involved and it's hard to describe via text >__> If you have to move *in* to her to do the b-air, then that involves a WD and can take awhile. This is best if she's floating far away and is a little complacent. It also DEFINITELY puts you over her if you whiff, which is scary. If you are full jumping into her at close range... you should be getting n-aired, or jabbed, or something. I almost always prefer to retreat as I b-air, because it gives you the coverage to land and be safe.
But then, I take big swings and risks when I play because I frequently forget all the things I just told you. So I wouldn't use *me* as a great example.
edit:
Regarding AZ, we've all got a bit of weirdness to us. Jetfour probably does the most non-useful extraneous movements, which throw lots of people off. I use the opportunity to just hit him, typically.