One problem with Padme is that she doesn’t really do much in ROTS. Most of the scenes where she does anything significant (negotiating with other Senators to form a proto-Rebel alliance) were cut from the movie. And even if those scenes remained, they really have no impact on the plot of RoTS itself.

I think Lucas just didn’t know what to do with her. The main problem from a writing standpoint is that all the main characters in the Prequels - except Padme - are super-human Jedi. It’s hard to write her into the story and have her do anything to drive the plot, except in the political arena. Even in AoTC she mostly just follows Anakin around after Act I. They integrated her into the action scenes at the end, but it was kind of clumsy because she’s not too helpful in an action scene when everyone else is a super-human Force user. Her character was best utilized in Phantom Menace, where her decisions and actions largely drive the plot. But in AoTC and ROTS, there was very little for her to do in the Jedi-centric narrative.

And of course, she doesn’t even have 1% of the personality and chemistry of Leia.

Anyway, the best female characters are in Andor. Mon Mothma and Dedra Meero steal the whole show in my opinion.