i know next to nothing about these other verses, so i have no idea on what to vote for
If you want a more generalized summary of the tone of each verse, I'll give it a shot.
RWBY: Anime Magic Highschool for Monster Hunters, people have superpowers based off their soul, world is a mishmash of elemental stones and technology. Story will start lighthearted and mostly slice of life, but will escalate to world-ending stakes eventually.
Honkai Star Rail: Science Fantasy Space Roadtrip on a Train, people gain superpowers granted by deities which are embodiments of ideals, technology varies wildly between each world/planet. Can be indistinguishable from magic in many cases. Stories can range from deeply dramatic and tragic, to fun and goofy.
P5: Urban Fantasy Heist Movies set in Modern day Japan, people gain superpowers based off their idea of rebellion. Vigilantes punish corrupt authority figures and criminals by literally stealing their desires and fighting their inner demons. Story oscillates between slice of life school life, and dramatic heists.
Generally, I'd consider Bad End Shriou to be the strongest respectively in P5 (since he'd have pseudo-servant abilities and magic in a world full of ordinary people), whereas Star Rail is probably the setting with the largest amount of people on par or stronger than him.
Personally, I like Star Rail the best out of these three choices. Placing Bad End Shirou in a world where people literally become stronger the more they embody/believe in a certain Ideal is extremely ironic, and also works perfectly with his character. And it also means that Shirou can still be the scrappy underdog at times.