Not sure if I follow this. What does kaiser have to do with hime ordering? Usually you order himes by speed to optimize time to burst, but if I'm not mistaken, all the himes in consideration here are pretty much the same speed (exception is water Cybele, depends on whether you cleanse her debuff.) In that case, I usually order by AAB consideration, which is you want all the buffers up front and as many red abilities towards the rear as possible to maximize dmg output. So yes, you would want buffers like Nike in front of Ryu-Oh who has all red abilities.
Ryu-Oh covers all three of those already and water Cybele covers frame B debuffs, so Ex PF is perfectly reasonable here. Just make sure you get Herc's axe, PF is hard to pull off otherwise. If you LB the axe, you can also hit the def down cap upon burst with that water team.
Another possibility for Ex is the skill that blocks an affliction (forgot its name) - normally it's a very bad skill to use as it's single target only, but since you pretty much have everything covered here, having the block up on water Cybele before using her 3rd skill can make her a burst leader instead of in the back row.
You can't build a 'best' team without knowing what you're up against. Also, are those your only legendary souls? It's unusual to have unlocked Shingen and Morgan without having unlocking most of the other souls already. Here a few things to consider:
- It looks like you have no one with frame B debuffs, so if you're going against stuff that can be debuffed, you probably want to Ex Sniper Shot, since you have neither Samael or Satan AW to pair with Amon U to hit the def down cap
- You have enough himes such that dropping Sol probably makes sense (unless your Sol is AW? but even then...) If you can't just run something over with FB, you might want to consider using Manes for heal or just block the dmg with Cernunnos instead so your entire team can make use of dark weapon skills (I'm assuming you're running a dark weapons grid and not a rainbow grid or something)
- Morgan is not a good match for what you have here, not enough DATA to make rampaging better than bursting with Shingen