Who would be yours? You posed the question to us, but you did not answer yourself.
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My answer is most likely Twice with 'dark / gothic / girl crush / baddy' concepts similar to Purple Kiss, Dreamcatcher, etc.
Why? Because..... it seems like they've always stuck with one concept--- retro-- and it's been benefiting them well, which is great that fans still love it.
But, I'd always imagined what it would be like to see them do a comeback or debut with one of the aforementioned concepts above and showcase their versatility.