Since no one ask, i will offer my opinion.
For me, these are the criteria for a handgun:
1. No external safety. This will only hang you up at the wrong time when you need to pull the trigger.
2. Since i always carry with a round chambered, a glock-trigger or 1911 trigger is just too sensitive (aka easy to go bang) for me. So, i prefer a DA/SA or DA-only trigger for safety reasons. I don't want to get stuck by external safety, BUT i also don't want a trigger that can easily be pulled by adrenaline. Basically, i want a trigger that only fires the gun when i truly want to. (DA = double action; SA = single action)
3. Caliber that is cheap enough to practice. In other words, .40 caliber is a great caliber in a handgun ("just perfect" in goldilock's term), but too damn expensive to practice. And as noted above, practice is everything in handling a handgun. No practice = worthless for me.
4. Caliber must be strong enough to stop people...yet, controllable. So, for me, 380 is too light, even in +P. I would choose either .45 or 9mm. I chose 9mm because it is cheap and in +P hollows, it is fairly effective at stopping bad folks. A .45 is nice, but the kick (recoil) is too much for me to be accurate. This may not matter in a close range confrontation...so, others may like .45.
But, for a home defense gun and a first timer, i would recommend either a shotgun or a revolver. Our home gun (for my wife) is a Ruger SP101 revolver with 38 special. (It can hold .357, but it would be too much for her.) Revolvers are reliable and easy to use...yet the trigger requires a deliberate pull before the gun goes bang. My gun safe at bedside has the Ruger and Sig P239 all the time. Both are loaded...and the 239 always has a round chambered.
YMMV.