You mentioned Springfield XDM, and I have had very positive experiences with Springfield handguns. I carry a XDs every day, and have an XD in 9mm as home defense.
However, I won't say "Buy a springfield!" because it's like saying Levi's jeans will fit you best. Only you can determine what is going to fit you best.
I will, however, advocate striker-fired pistols for their simplicity.
I have my opinion like everyone else. However I won't express it as I see it pointless several pages into the thread. Only advice I give is make sure the pistol you buy has a rail so you can mount a light
Glock 17 or 19 is a great choice. Very dependable, tons of aftermarket stuff, and low cost.
My 2nd choice would be a Walther PPQ M2
The Walther will surprise you on how great it is right out of the box.
Nice trigger, great ergonomics, and dead nuts accurate.
Sig 226, CZ75B, or a Smith M&P are also great choices.
Go to a gun range where you can rent different guns to try.
If you are in the Indy area, go up to the new Point Blank range in Carmel.
Nice place and a good selection of rentals.
I only own 2 9mms, and they are both Walther PPQ's. I would put that on the list to handle and shoot if possible. I would not discount any of the suggestions made in this thread either. If you get a chance, try them all.
Don't be be afraid to make the "wrong" decision either. Get in the game, figure out what you like and don't like. Buy that M&P, for example, then shoot your buddy's CZ. Along the way you might figure out that you've found something you like better than your original choice. It's hard to really know what you like until you've carried one, trained with one, and put some rounds through it. Now you can trade in that original purchase, or with any luck, you've got enough by that point to purchase the new one outright. I've owned a number of pistols, and it took me all of them to figure out what I was looking for in a defensive handgun. But maybe that's just me being a slow learner, too.
1 gun for good? I'd have to say G17 or G19. They are out there with over 100k rounds without breakage. That about says it all, to me. Simple, reliable, durable. Not the most accurate, but for all purposes, if only one allowed for the rest of my life, the Glock is my choice. (I actually prefer shooting my SR9. It has a much better trigger, and I'm more accurate with it. All 3 I've owned have been 100% reliable, but will they go 100k rounds? I have no idea, and probably never will.)
Henderson Defense in Las Vegas rents guns to tourists. The owner says the Glock 17, hands down, is the most durable and reliable gun they have, with only the Beretta 92 being comparable. He said all gens of Glock 17's have gone over 100k. They broke a few slides around 100k, but he thinks that would have been avoided had they replaced worn slide springs.
They don't run all the pistols mentioned. Just the ones tourists request frequently. No Glock 19's, for example. I just suggested it because it is essentially an identical design to the 17, and I like its slightly more compact size.
I only own 2 9mms, and they are both Walther PPQ's. I would put that on the list to handle and shoot if possible. I would not discount any of the suggestions made in this thread either. If you get a chance, try them all.
CZ-75 or any of the number of clones out there. My first pistol was my IMI Baby Desert Eagle purchased over 25 years ago, and it's still my EDC. I've bought and own many others over the years, but nothing beats the ergonomics and thin design of this pistol.
The question of 'What should I buy?' is getting to be tough to answer. There are so many good choices that it's hard to go wrong with any of the mainstream guns. It really comes down to the fact that choosing a pistol is like choosing a spouse. There are lots to choose from and you can live with many of them even if they are not ideal. But, if you put some effort into testing the waters with as many as you can, you might find the one that fits perfectly.
Chances are, you'll probably do well with any of the common pistols today. Afterall, most Glock fan-boys would be M&P fan-boys if that's what they had first. Same for XDs, Sigs and others. CZs are a bit different though, since most seem to find their way to the CZ after trying many other pistols. The only real way to know what you shoudl buy is to try as many as you can. Trying to tell you what would work best in guns is like asking this group who you should marry.
For ease of use, you'll probably want to discount the DA/SA and the SA firearms.
Easiest to use are those that either DAO or striker fired.
While I'm rather out of touch when it comes to what's offered in a DAO configuration these days. As for striker fired, again for ease of use, you'll probably want something without an external safety. Think Glock or S&W M&P (no safety version) or HK VP9.
If budget is in play I'd recommend a Ruger SR9-C or an M&P Shield. Both are around $400 new and are reliable. Then you'll have money left for ammo (lots of ammo!) and training.
From what I've owned/shot/carried/witnessed it would be a Glock 34 Gen 4. A fantastic shooter right out of the box and a staggering amount of factory and aftermarket parts and accessories available for all manner of Glock. Nothing ruins and awesome deal on a pistol when you can't find a quality holster for it. Anything and everything is available for a Glock to customize it the way you want and if keeping it bone stock is your thing then the 34 is a beast right out of the box. You can still everyday carry it with the proper clothing, belt and holster and going IWB makes it a bit easier. Full-size for range and training is always a plus and despite being longer than a G17 the slide weighs less than a standard G17 slide. It may not look like much but it is easily one of my favorite guns I own.
there are some incredible 9mm out there like the Springfield XD/m, the SIG P226 and others but considering all factors going Glock is probably the easiest and most no-brainer-ish of them all.