Ayra or Hinoka?

Since I don't know your priorities, I'll consider it through objective reasons.

Ayra is a great standalone unit, that doesn't get hurt by bad IV that much, she has a legendary weapon, high tier special and inflated BST, meaning that she'll grant quite a lot of points in arena. She's also just an awesome offensive unit, that can solo entire enemy teams with correct support thanks the extra dmg coming from constant special triggers. The biggest disadvantage she currently has is that she shares focus color with Eldigan, which could cost you your patience and your soul.

Hinoka on the other hand could get crippled by a -atk IV and mostly works only in flier teams (unless you invest heavily in her to give her different skills). In a flier team she can both benefit from flier buffs and grants one of the most important buffs as well (hone fliers). By that I would conclude that her use will be kind of restricted since she won't fit to as many teams as Ayra would. The summoning benefit comes from the fact that she's the only focus unit in her color bracket, meaning that you have a higher chance of summoning her.

With that conclusion I would objectively choose Ayra.

It depends... Ayra is a monster on the offensive, kinda like hinoka, but do you need a lance or sword user?

I'm going to disagree and say Hinoka. She has a very valuable inheritable skill, and is the only one who carries it, so if you get a garbage IV Hinoka at least your +10 Clair will be more useful.

You'd be pulling them for almost entirely different reasons:

Ayra: Amazing standalone red infantry nuke. However, she competes in a really crowded space even as good as she is. She's also meh as a defensive unit in Arena based on my experience thus far, as Lyn and many fast mages can still double her and tanky blues and even some reds can soak most of her damage (My Sigurd has been fairly easily dispatching her so far).

Hinoka: Holder of Hone Fliers, the key to unlocking the true potential of Flier Emblem. Outside of that though, Tana and Cordelia (and even Subaki and Est to some extent) are all really strong/better candidates for a blue flier unit.

It basically comes down to if you're looking to build a flier team. If you are, this is a no brainer and you should go for Hinoka, as the community has been waiting for months for this banner and we don't know when she'll be back again. Hinoka also isn't sharing a color with a less desirable unit.