PA!Inigo or Loli!Azura?

Depends on what you value. Youngzura has a prf weapon so she'll score better with G Duel. Though expensive, she's also more accessible since Inigo's a seasonal.

If Rein and Brave Lyn are still an issue for you, Inigo handles both otherwise Azura is somewhat better.

I think it depends on what IVs your Inigo has. With her tome Azura has 1 point less in speed but arguably better offense and good resistance. Inigo is better suited for countering bows and daggers because of his better defense. If youre Inigo is plus speed he might be worth it, you can boost it further with a +spd refinement and he shouldn't be doubled too often. Azura on the other hand can perform really well with her base kit already, if you are good at repositioning that is. In the end it's a question of which unit you like more I think, but as soon as Azura will (probably) be available through Heroic Grails, you might have a better time with her.