For me it’s NO CONTEST: John Powell’s theme in X-Men III: The Last Stand for Jean Grey/Dark Phoenix. Holy shit!!! Particular favorite moment of that theme in the score is 2:28 into this cue: https://youtu.be/drPGnQLVIK4
Are game scores allowed? If so, Juliette’s Theme is my favorite thing Michael Giacchino has written in the past half a decade or so… particularly powerful starting halfway through: https://youtu.be/XBmHJwqayMg
I still don't know what you mean by 'powerful'. 'Powerful' and 'woman' are two words which I wouldn't use in the same sentence (other than this one). I guess Marion's Theme is my favorite theme for a woman.