Tough question. My wife likes my Taurus 92 in 9mm because it doesn't kick as much as the SW99 in .40S&W I personally can't feel the difference and I like the ergonomics of the SW99 much better. I would say start her off with either and some subsonic ammo. There are a lot more choices currently for 9mm ammo but the .40 isn't far behind. If you are worried about recoil, don't get a Polymer framed pistol. The metal frames will absorb more felt recoil. Same goes for barrel length. Longer barrels will feel like there is less recoil and not as "snappy".