Are you looking to own a gun to keep at home, or to carry? Because that makes a difference.
You'll hear a lot that a .22 is worthless, and that you need to get something heavier duty if you want to make an impact, but you really can't go
much bigger than a .22 for carrying and then actually, well,
carry. I carry a .22, and even it weighs down my purse quite a lot. It is true that a .22 won't be the same deterrent as a larger caliber, but you have to pick something you can use. The first gun I shot was a .40. It was SO comfortable, it felt like it was made for my hand. But I never once mastered shooting it without it flying backward from my careful grip. And I'm not dainty.
I would recommend going to a Gun Show, if one is nearby, just to handle different guns. Whatever you choose should be something you're comfortable with.
I carry a
Link Removed, and I love love love it. I bought it mostly because it just fit my hand so well, and was extremely comfortable for me to hold. As for carrying, not only is it fairly small and compact, but it is soooo easy and accurate to shoot. In shooting other guns of various calibers before this one, I definitely always felt like I needed a lot more practice to get comfortable with them. With my Ruger, I was hitting the bullseye in the first magazine. Love it. Even men at the gun range were coming over and complimenting the choice and saying it was a great piece. Lastly, the magazine holds plenty of rounds, so in an emergency situation, or some drugged out crazy coming straight at you who won't go down, you're less likely to run out before it's done any good.
One other thing is just an idea I have. I haven't tried it, so I can't recommend it, but it might be worth looking into. If you're looking for larger caliber for higher impact, but don't want to carry a huge, heavy gun around, you
might look into a
Bond Arms Derringer. They are pretty tiny, and only 2 shot, but my understanding is that you can swap out the gauge to hold bullets of different sizes. 2 shots with a .45 might be more effective than 12 shots with a .22. But, again, I haven't used one and can't speak for them.
Good luck!