Glock 30: .45 cal subcompact, 10+1 double stack magazine, with trigger safety* and two internal (eg you can’t drop it and have it go off) safeties, as opposed to button or switch safeties that I don’t particularly like on handguns. It’s reliable, takes <5 minutes to clean (and learn to clean), and is practically indestructible. My wife is small and has no problem handling it, since 9/10 of it is form and practice. I’ve had no problem using it to teach men and women of all shapes and sizes how to shoot.
At the time I bought it, it was a real no brainer, since I wanted a combination between 10 round magazine (the Clinton ban was in place), the biggest round we could safely and cheaply manage, 100% reliability, and a moderate level of concealability (if only because I have a concealed carry permit and I would rather carry it on my person when I took it to the range, since I used to go by bicycle). Despite the first factor disappearing, I’m still extremely happy with it, and it is my home defense weapon of choice.
Kahr PM9: Glock clone, 9mm, no trigger safety but similar internal safeties as above, 7+1 single stack extended grip mag (one of the two that came with it, the other is too small for my hand) . With high grain JHP rounds I have absolute confidence in its stopping power and penetration, and it is very concealable year round. Mostly we bought it due to the false belief that anything above a 9mm would be unmanageable for my wife, but it ended up working out in terms of what I end up carrying on the rare occasions when I feel I need to.
semiautomatic only m16 version, homemade, 5.56, 30 round magazine, etc. Because I didn’t want to lose all of the skills I worked on in the Marine Corps, and it’s a really fun intro weapon for friends and new shooters. And for me, of course. Not practical in any sense for home defense unless there is a zombie apocalypse, but when that day comes I’m ready. Also, ammunition is particularly expensive thanks to wars.
I’m not going to argue about it much, but for me at least a shotgun is not a particularly compelling home defense weapon. It builds a false sense of security with respect to wall penetration and ricochets, it’s not particularly easy to handle around corners, and for anyone who has practice a point fire weapon is superior in any situation where you care about collateral damage. Many people who have practice and are far better shooters than I am will tell you otherwise, but unless I was also a hunter or simply enjoyed shooting them recreationally as well, I don’t think a shotgun is worth it. You’re not going to get anything but a taste based conclusion in the end, so try it out and see if you like it. I don’t, at all.
Finally, if you are just learning how to shoot, see if you can find a friend or acquaintance who you think has their head on straight to teach you. Better yet, take a class. You can learn with virtually any standard model of handgun, but bad habits are a real pain in the dick to unlearn later and they stick really fast.
*a trigger safety is a lever in the midst of the trigger that has to be fully depressed before the trigger can be pulled. It is my favorite handgun safety.