I daresay it's the costume that attracted the notion of "Mander Woman" being a thing. Short skirt, small waist, prominent boobs, long hair, shiny headdress. See, it's classic drag getup.
Wonder Woman is supposed to be a powerful woman. Surely the idea of a trans character as a superhero should involve a bit more thought other than "ooh let's make her trans" - that's so lazy. Get your own character and keep your mitts off the women!
However, if you insist Man-Woman must stay, let's have a trans-identifying female taking the place of Hulk (little Hulkie) or Thor (shorter Thor), shall we?