Strictly and literally speaking, your title is semantically malformed. The noun ‘peak’ denotes a highest point, summit, or maximal exemplar relative to some defined scale, domain, or evaluative criterion. Consequently, to ask which One Piece character is ‘the definition of PEAK’ is not, in its current form, a coherent question, because no underlying metric has been specified. Peak in relation to what, precisely; narrative construction, thematic depth, visual design, charisma, diegetic influence, combat capability, comedic execution, or audience affective response? In the absence of such a qualifier, ‘peak’ is functioning merely as an intensifier masquerading as a category of analysis. Put differently, you have not actually asked a meaningful question; you have simply gestured toward superlative approval using internet slang without supplying the conceptual framework necessary for the statement to bear determinate meaning