Male? Female?

Lots of women ride bikes with a straight top tube. No sense in reserving the "racing bikes" just for men.

Some men ride Mixte bikes, and prefer them.

The biggest benefit for a step through/Mixte is if one chooses to ride with a dress or skirt (or kilt). If one is riding with pants or shorts, then the straight top tube bike should be just fine.

In many cases, women are a little bit more flexible than men, so they shouldn't have any problem getting on and off.