Go to a range and rent several, put a box of shells through each and buy the one you shoot best.
Some that I would suggest you try in the bang for the buck category would be.
1. Ruger P90, this is what I carry and it has never failed me. Built like a truck.
2. Ruger P97, synthetic frame, three ounces lighter than the P90.
3. Ruger P345, synthetic frame, I didn't like the feel of the one I tried.
4. 1911, Springfield or used Colt or any of the other reliable pistols out there. I retired a 90 year old Colt 1911 when I got my Ruger, haven't regretted it for a second, though I do love 1911's.
5. Taurus Millenium Pro (Pt145?) this is one of the best in-the-hand feeling guns I have ever held.
6. You might even try a Glock, I have never found one that felt right in my hand, but you might.
The thing is that we will all tell you which guns we like best. None of us is wrong, for us. The trick is for you to get the one that is best for you. The only way to do that is to try a bunch of them. Fortunately, this is fun.
Of course you could just go out and buy the first one you see and learn to shoot it good enough to defend yourself.....Maybe. But go have some fun and get the right one the first time.
Let us know what you decide.
DM