I do have them all, and undeniably use Iphi more, but also keep in mind that Iphi is a substantial enabler of many of the new, modern style of Meta chars where more damage is done outside rather than inside of AF - which I find a helluva lot more fun, compared to pianoing in AF!:-P - so like Yakumo + Iphi and Sesta + Iphi and Minalca + Iphi etc. are all significantly better teams than without Iphi. Iphi also offers a great deal more in her kit than a mere DPS, meaning that she will hold onto at least one of her many roles during battle much easier, e.g. Iphi + AS Necoco can turn your entire team into shade-dealers to substitute for Yakumo. Iphi also offers the most UNIQUE utility among these three, or among any character in the entire game really.

I almost hesitate to reveal this spoiler but since it may be a crucial part of the answer (anyone skip forward to the next paragraph if you truly do not want to know…): AS Melody is coming in the next update, who will also deploy an awakened wind zone, and will be the first character in the game who can do so reliably over & over again (although not on turn #1 iirc). And also AS Noahxis is coming in the same update, who will offer the game’s first free/story character option for barrier piercing. So part of Sesta’s charm is already starting to wane, or at least someone could try to argue that, but really what it means is that Sesta + AS Melody will work together to become unstoppable, being able to re-deploy wind zone sth like every 4th turn! (and if RCF was on the front-lines when it was deployed, it will last all the way through to the next one, b/c he extends another zone +2 turns) Sesta really is so “fun”, like a big puzzle to connect her to so many other characters in the game:-).

Don’t forget that Yakumo has a side-kick, like Minalca, except in his case it offers a more specific pairing with him than anyone else. That said… skuLd was telling me about a 1TnoAF for Wyverus using Kumos’ Break status, even without Yakumo on the team. Kumos helps cover for a LOT of Yakumo’s inherent failings - see e.g. this video of his for a REALLY hard superboss, and note how Iphi helps keep him alive outside of AF. She sets up both P&P and Type resist and stat mitigation, in a different skill provides mental focus while also deploying shade zone and also reinstating blood contracts on everyone, and the description of her kit just keeps going on and on and on (offering knockback resistance, barrier piercing to others, etc. -> much of which while not unique is still extremely useful; and some like shade zone setting IS unique!:-P). Don’t get me wrong: Yakumo still has a TREMENDOUS amount to offer a team all on his own, but yeah his MP would get depleted a helluva lot faster inside AF (without Kumos being able to regenerating it), if he did not have someone (Prai, AS Radias, AS Soira, etc.) tanking for him to keep him alive outside of AF - plus also note that he has an MP shell, which sounds nice for his survivability except that too further depletes his MP, thus it occurs at the expense of his DPS. Also he isn’t great at 1TnoAFs, needing someone to set that for him - like ES Mariel, AS Milsha, etc., although once again, Iphi can get it done for him, which she actually does automatically upon battle start, and also whenever she chooses again later (his pet can also do it, but not upon battle start).

Of the three, the one that I like the most and “enjoy” the most is Sesta… but in large measure that is b/c she can get it done WITH Iphi’s support, who again is the best at enabling that noAF style of play that I enjoy with her (although again, there ARE other defensive supports, just none that are all-around as good, plus Iphi actually pairs well alongside them - e.g. diverting attacks onto AS Soira, who then negates them; also I should add that about half of my clears use Sesta without Iphi…but the absolute HARDEST content needs Iphi). But purely for utility, it is Iphi who is the mainstay of most modern teams. In fact, the main reason to NOT get her is if you felt that it made the game too easy… and yet even then, she offers a great and fairly unique character quest, so she would still be a good choice for an SDE.:-)