No such bike exists!
My '74 Yamaha Cafe Racer
Okay, so why would anyone think there is a "best" bike for a woman...it all depends on the woman, her riding style, her experience, and he height and strength.
For overall agility, ease of learning, and quality for the money, though, it's hard to beat a Kawasaki Ninja 250. I've been riding for over 30 years, on everything from mini bikes to a Z1000, but the li'l Ninja is one of my favorites, even among my vintage 2-strokes!
Speaking of which, it's quite empowering to build your own "dream" bike, which I've been doing for some time....it'll be finished, some day!
Here's a pic: