Buying a gun is a personal thing. Buying a gun for CC is an even more personal thing. How well you conceal a gun depends on your body, and the style of dress. One thing that is important is that you get a gun that fits your hand well. This will allow you to point it more naturally. However, many people have guns that don’t fit them in such a manner and get by fine. Sometimes they just learn the gun.
When looking for a new gun it’s important to determine how you plan to use/carry it. When I went looking for a CCW I tried out holsters at the same time. I covered the weapon and looked in the mirror while sitting and moving around to see if it would print or not. In essence, I determined ahead of time exactly how I was going to use and carry the weapon before I even when shopping. Then, when I had made that determination did I go to the gun shop and look for guns and holsters that would work for me. Combine that with how the gun fits in your hand, and how well you shoot it.
Another thing to consider the availability of parts and accessories. Holsters are a biggie here as that is how you will carry the gun. Springs fly away, and small parts break. Know where to get the parts, and what to do with them once you’ve located them. Glocks are easy to work on, and parts are cheap and readily available. The others may be also, but I’m not familiar with them.
You sound like you are fond of .45 ACP or .40 S&W, and that’s fine. They are good rounds but, also understand that they are more expensive to shoot than a 9mm. For some people that is an issue, and for some it isn’t. Some people even buy a .22 just to practice with. There’s a lot of things to think about when buying a gun.
The guns you’ve listed should be fine. I personally wouldn’t trust the M&P just based on the problems I’ve heard about on the net. I know only one person who owns one, and he has had no reported problems with it. Take that for what it’s worth. Were I to buy and M&P, I’d want to put at least 1000 rounds through it before I trusted it. There are people who have M&P’s without any problems, and then there is a whole sub-forum dedicated to it’s problems on the S&W forums site. It’s probably like any other weapon in that you should shoot it enough to become familiar with it and be able to trust it.
If you like the G21, you might look at the G21SF. It’s a slimmer frame, and has a reversible magazine catch. I know you didn’t put it on your list, but you’ve listed two subcompact guns (the Glocks) and two service size guns. It’s kind of like the old “apples and oranges” cliché. Either way, the Glock has been time proven, and there is a lot of parts and accessories for them out there, so you should be fine with any one you choose. If it’s for concealment, then you probably want a smaller frame, but if it isn’t for concealment, then why not go with higher capacity. Something else about the Glocks is that if you get the .40 Glock, you can swap in a conversion barrel and run 9mm for practice. I don’t know if it’s possible with their .45, but it might be something to look into.
The XD has a different grip angle than the Glock (as does the M&P), and it also has the grip safety. It’s trigger pull isn’t a much as the Glock because it is more “cocked” than a Glock. Like the Glock and the M&P, there are a lot of XD owners out there who trust their life with them and will attest to their greatness.
The fact that you’ve listed two different sizes of weapons (subcompact, and service) seems to indicate that you either still aren’t sure about the potential purpose of the weapon, or your thinking that it will serve a dual role. That dual role being concealed carry, and home defense. Most people don’t use a full sized service weapon for CCW, but there are a lot of people who do. If you can make it work, then more power to you. I suspect this is why the manufactures came up with the compact size (between the service and sub compact). As an example, i can use a G19 (9mm compact) that will work (for me) as a CCW piece, yet still fill the need for HD. As with most of the weapons you mentioned (exception being the slim line Glock),the G19 can take mags from the G17, or just use some pierce grip extensions to increase capacity.
Bottome line:
Go with the one that suites you the best. If you don’t mind spending the extra cash on .45 ammo then get it since you can shoot it (I mention this because you talk about practice), and it‘s suggested to use the largest caliber you feel comfortable with. Know before you buy (by trying it out in the store) exactly how you are going to use/carry/conceal this weapon. I have a friend who bought his first CCW piece last year and isn’t happy because he now realizes it’s too big for pocket carry, and he doesn’t like Hawaiian shirts. You might consider this when looking at the service size.
I wrote this before the crash yesterday, and now see your onto the idea of having two guns. This isn’t a new idea and it’s sound logic. Your needs for a trail gun may not be the same for something for home/personal defense.
The suggestions for .357 for a trail gun aren’t all that bad. Ted Nugent carries a 10mm for that purpose. Again, go with the largest you feel comfortable with, and understand the limitations of the weapon before buying. Don’t limit yourself. There are a plethora of options out there, and it can be advantageous that you know what the limitations and advantages of each gun/caliber are before you buy.
P.S.
corneredcats blog is excellent reading.