All of the options are extremely useful for us right now.
Lighting turns us into a murder blender that can spam the shield to tank blows. It'd probably give us the side benefit of a more physically powerful sword style because we can leverage more force without hurting ourselves, the extra energy absorbed into the shield, and do it constantly because the shield is so cheap. Honestly it sounds like a pathway to the physical amps of the lightning cloak with a bigger focus on defense than the original jutsu.
Wind turns us into even more of a murder blender than lightning, with possible direct speed and flight buffs. It also might give us the side benefit of using blades of wind in a free form manner and might enhance our sword techniques. It sounds very promising for investing into raw killing potential in the future, possibly being able to build off of the wind blades to form easy sword beams.
Earth turns us into a tank, which at first glance seems less attractive than the other options, until you realize that it'll save us from crippling wounds that are one of the last remaining flaws in our speedy fighting style. Whereas the first two options aid mook to mid-tier slaughter, duels to an extent with the lighting cloak, it's the rock armor that'll truly let us punch upwards and fight in close quarters with S-class. We have found that those who can match our speed force us into situations where we simply have to tank hits, so breaking bones every time that happens is a major drawback.
The lighting helps us use the shield more which is very attractive considering earth will severely hamper our endurance potential if we are forced to take hits. But so will broken bones, so in both cases Hisana will end up on the backfoot long term against Kage tier monsters. Ironically, wind is more attractive for endurance since it'll improve speed and therefore dodging, but that will only go so far, essentially raising the bar for who she can take on without needing to block attacks, but still useless when that bar is cleared.
It's a really tough call.
I'd say lighting is the better all rounder, and definitively the best for dealing with mid-tier to elite jonin opponents, probably people on par with or slightly above kimimaru in raw stats. but it has the issue of not blocking very harsh attacks completely, so it's only useful for weaker attacks that are fast enough to hit Hisana, which seem more like desperate gambles from scrub ninja, or light boxing from OP ninja, making it more of a setup ability. If we are fighting an OP ninja it'll let Hisana tank the weaker attacks long enough to deal a finishing blow whilst enduring them, or it will let her endure a powerful attack once, in order to deal the same lethal blow. In a way it's very all or nothing in that situation, so it's the more risky pick when punching upwards. Because the way i see it, hisana will be nice and defended 24/7 with the cheaper shield, but any attacks that can powder her bones past the shield will still be very effective, so now she lacks the speed/offense of wind and the durability of earth, so she's at a major drawback compared to those choices in this fight agaisnt the stronger opponent.
Wind seems like the sort of pick that can lead to all sorts of goodies in how both offense and speed can be boosted, so it seems a bit more esoteric and indirect in how it'll help Hisana, turning her into a glass canon. That's because the main benefit beyond slaughtering mooks, is to let her fight faster S-class on equal footing and hope that they don't force her to eat any shots that could kill her, or force her to break a bone and expend lots of chakra for teh sheild. But at the same time, the offensive capabilities actually give her massive benefits in that scenrio if she pulls it off. So i'd say due to how it lets her blitz high to mid tier opponents it is more consistently useful than the lighting cause she will never get hit by them, and if she does she can tank the hit once. But it's ironically more risky for fighting stronger opponents because it puts her in the zone of being able to keep up with them, making her a priority target, but doesn't give her much chance of surviving if she gets unlucky or outplayed.
Earth seems like the more focused offensive option of the bunch, giving Hisana better survivability at the cost of combat endurance, and letting her more confidently fight S-class ninja knowing she can take what they can dish out at their max and shrug it off. i don't think it'd put her on par with the opponents that wind would let her fight, and she'd have a poorer showing agaisnt them than with wind, but she'd actually be safer vs them until she runs out of chakra, because although slower, she is actually eating much more lethal attacks without really flinching from them. So the hypothetical OP Kage is more able to dance around her but also can't pin any lethal or debilitating attacks on her, giving her a better performance than with lighting, with less risk of death then with wind, up until her chakra runs dry. There is the added drawback of the chakra cost limiting her other options though compared to wind, and especially lighting. So assuming the opponent might be the sort you can escape from with use of powerful jutsu, it'd actually make her less evasive than with lighting.
Currently i'm actually leaning towards earth despite the fact that it'd limit her roster of jutsu more, reduce the potential killing options with lighting and especially wind, and massively tax her chakra reserves making her very vulnerable to tiring out vs powerful opponents. That's because imo, it's the best option for taking on, surviving, or even killing stronger S-class ninja that we would not otherwise be able to take on, assuming we can end the fight fast enough. Wind in my option is the best of the three until the enemy gets in a few lucky shots, which as we've already seen, can be easily forced to happen when you enter the big leagues of speed - Sure wind increases how big those leagues need to be, but i prefer an option that is more reliable. Lighting on the other hand, although much more effective quantitively than the other options due to the chakra cost savings + potential to weaponize lighting, allowing you to dominate more scenarios, it is too much of a disadvantage vs S-class opponents who can grind Hisana down through a shattered skeleton. If they are capable of doing that, more chakra reserves are unlikely to matter in terms of making an escape route.
Better to survive the lethal predator and escape unscathed, but as a loser, than enter a dance of death with them and possibly get beaten over time by their superior stats. My other reason for choosing earth is that it will lean further into defense than the other options which should be our main priority for the shield, and the cost issue can be solved later hopefully, so i'd much prefer to have the durability now, when it might be more needed in a future fight.
I also think that an earth derived energy barrier could look cool if it leans into a metallic red hot molten chakra colour, to contrast Sasuke's purple and Naruto's gold.
Tldr:
Earth sacrifices time for ability, with that time proportional to the number of hits she endures compared to her chakra capacity. So it's actually the best choice for fights that are shorter than that time limit of her chakra capacity when tanking hits. But it'd the worst for fights that are longer than that.
Long fight vs slightly OP ninja (Hidan tier? Maybe Fuu tier?):
1. Lighting
2. Wind
3. Earth
Short fight vs slightly OP ninja:
1. Earth
2. Lighting
3. Wind
Long fight vs actually OP ninja (A hokage, Jiraiya?)
1. Wind
2. Lighting
3. Earth
Short fight vs actually OP ninja
1. Earth
2. Wind
3. Lighting