Alucard
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I think all the listed ones (except perhaps Yutsuken) are just phlegmatic; the concept of "seriousness" encompasses many things. Alan leans towards another nomination; he only exhibits calmness, and not always.
As for the "top five," I doubt it; they all know each other very well.
P.S.
Apologies for deviating from the rules.
Нет, я же Гитлер.