I offer another vote for Glock. I was a gun buyer back in the mid-1980s when Glock came to this country. The company I worked for was one of the first distributors for Glock. I personally owned one of the first Glock 19 handguns ever brought into this country. Over the years, while working in the gun industry, serving in the US Marine Corps, and being a police officer, I have owned or fired nearly every commercially available firearm you can name in the next five minutes...
So, with all that said, I believe that you will be best served with a Glock 9 mm, from the 17/19/26 family.
Think of a handgun as a "platform" rather than an individual item. When I say platform, I mean you will buy magazines, ammunition, sights, lights, lasers, et cetera. With a Glock, there is a dizzying number of accessories you can add to the gun if you see fit.
Reasons to buy a Glock 9 mm are these:
1. 9 mm ammo is one of the cheapest centerfire handgun calibers you can buy.
2. Glock 17 (17 shot) magazines can be purchased for less than $20 from many different sources. Remember that you can use G17 mags in all 9mm Glocks. Also, while the 9mm cartridge may not have the reputation the 45ACP enjoys, remember the Glock can hold 34 rounds (with a 33 round magazine) in a dead reliable configuration that is still relatively compact.
Make no mistake, if you really need to fire in anger, having 34 rounds of 9mm hollow points on tap trumps having only 8 (M1911 platform) or 6 (most medium frame revolvers)
3. The Glock 17/19 has a reputation for being one of, if not the most, reliable firearm under every possible adverse condition. Don't take my word for it; the Internet is full of articles about torture tests against every other kind of semi-automatic firearm. Research for yourself...
4. Few firearms are easier to equip with a light, or laser and light combination.
5. Consider this scenario, and then do your own research... If you had to walk into a gun store, pick any semi auto pistol on display, purchase it, load it with HOLLOW POINTS, put it in your holster and walk out into the world, knowing that at any moment you may have to use that pistol to defend yourself or your family... Which would you choose?
Me? Glock 17 or 19 with no hesitation.