Like Krazie said, people are gonna have differing opinions, and here's mine:
A 9mm is a good choice. A .40 Glock is easy to handle, as well, but I can't stand the tiny handgrips. When I fired one, it felt like it was gonna jump out of my hand. For that, they DO make an extended magazine that gives you more to grip, but for me, it's not enough. I went from firing a 9mm M-9 in the Marine Corps, which had a huge handgrip, to a 38 Special, which felt like a toy! I love it, though!
Another suggestion, but also personal preference/bias:
If you have no experience with firearms, and want something that's low-maintenance, and very reliable, go with a revolver. They have very few moving parts, which leaves little to malfunction, and you'll rarely have to clean it (I just realized that I said almost the exact same thing in this same thread, a few days ago!). For home defense, I'd rather have the reliability of a 6-round revolver than a semi-auto that may have more rounds, but is more prone to jamming. If you NEED more than 6 rounds for a home intruder, you're probably in a lot more trouble than a handgun is gonna help you with!
I'll echo taking a firearms class. It's extremely important to know what your responsibilities are, as far as owning and potentially using a gun (You have to answer for every bullet that comes out of it! 😉 ). I don't know what part of Ohio you're close to, but I know a decent instructor in Dayton, if you're interested.