Best Corrin (F) IV's?

Take the first one, +3 HP seal is as always an easy fix to the HP bane even if it's -4 assuming she has that kind of treatment.

Apparently it's not the most optimal things to try to build her as an offensive unit, to which most people just run her as a tanky debuffer. Something like Fury takes her away from getting doubled from the grand majority of units at neutral Spd, and her neutral Def is about as good with it. +Spd gets her away from getting doubled from +Spd Fury/LD Lucina and Nino with Fury. +Def just makes her even more tanky, and may not even need Fury to further patch it up (could also compliment well with Fortress Def if you don't care much about her Atk).

The IVs look kind of contraproductive to me, and I'd just personally go for neutral (the one I have). She's been a staple for my older team back in the day and worked well as a maxed *4. You also have enough to make a 4*+6, which is the exact same of simply promoting one to *5.

I'm assuming this isn't the Summer Corrin, btw. I have her with +SPD -Res, and she's a bit of a monster. I have Fury and Swordbreaker on her, along with Threaten Res and Moonbow. Pretty standard, but she reaches 40 speed as a tank character, and can survive most everything I drop her into. Add on that she does magic damage, which is usually the weakness of what she'd be going up against as a tank, and she can do a very respectable amount of damage as well. Looking over your choices, I'd take the SPD+ one. All the others buff the wrong stat or weaken an important one, as you'd rather not get rid of SPD or ATK.

+Spd is pretty essential for Corrin as it basically prevents a lot of the cast from doubling her while allowing her to debuff.
She has great defense and wonderful speed for a hero and definitely for a dragon, and Dark Breathe is one of the stronger breathes in the game in terms of attack power, so it helps even if just slightly.

Attack power for Corrin isn't that special, so an attack bane really isn't that bad for her since it helps her perform her role much better.

Resistance can help her tank magic better, though her resistance is low in general and may not make much of a difference unless you consider giving her Traingle Adept for extra damage and protection against red mages. I think if you use +Res, give her the ability to tank red magic as much as possible. Julia will still mop the floor her anyway.

Fortress Resistance is a thing now if I remember, so take that into consideration if you like. With a boon and Fortress Resistance, she can reach 29 resistance without buffs in it. That's... above average I would think and could prove useful. I think she could pull it off with her stats all things considered. +Spd for her is still the superior choice I think.