For a long time, my wife carried a .38 Special snub-nosed revolver. She tried several different 9mm semi-autos over the years, but she never could find one (other than her Sig P239) that she felt was reliable, and her Sig P239, even though it's supposedly a "compact" semi-auto, is too big for her to easily conceal on her small, 5'1" frame.
Then a few years ago, right after Smith came out with their M&P Shield EZs in .380, our oldest daughter bought one for herself, and she loaned it to my wife to try out. My wife fell in love with it and bought one of own. That's not the end of the story though.
As soon as Smith came out with their M&P Shield EZs in 9mm, our daughter (probably with her husband's urging) "traded up" - she traded her .380 in and got a Shield EZ 9mm that she told my wife, "Doesn't kick any harder than the .380 I had." However, my much more experienced, and naturally older wife once again borrowed our daughter's new carry pistol, and she says, "It Does
Too Kick Harder!" So, my wife stuck with her .380 Shield EZ.
However, I need to explain that my wife, who is almost as old as I am (I'm 74) struggles with arthritis in her right thumb joint - probably at least in part due to the thousands upon thousands of full-house .44 Magnum rounds she fired in practice and competition during her IMHSA days back in the '80s. So, the .380 in a small package like a Shield EZ is plenty for her recoil wise. She doesn't have a problem with 9mm recoil in her Sig P239, but like I said, the Sig is bigger and harder for her to conceal.
Oh, and the other thing about my wife's Shield EZ is she has to grip it "higher" than what
used to come naturally for her, or it will stovepipe once in a while. So, my wife practices a lot, and gripping it "higher" (like she should have been doing in the first place)
does come naturally for her now.