Re: New to side arms. Need help.
I am a former HK USP and XD owner.
I liked the fire control on the USP coming from 1911s, but HATED the DA trigger pull. The answer to that is to carry the pistol cocked and on safe which leaves you with a crisp SA trigger pull. However, HK customer service is an oxymoron even at present as they try to improve it. I just sold my USP compact a month ago, but I am happy where I landed. The "compact" is anything but compared to other compacts. I REALLY wanted to buy into the hype, and the new P30 feels great, but it is not worth the price of 2 Glocks.
The XD is a reliable and accurate pistol, but has an insanely high bore axis which causes it to be less controllable in recoil than other models. From a concealed carry perspective, the old XD compact is fine, but the new xdm still hasn't figured it out. The frame is the same for both the standard and 3.8. Why? I have no clue. The barrel length matters little. That huge ass frame that they want to pitch to you for holding "19+1" or whatever the hell is useless for CCW. If this is simply a range queen and will be nothing more, they are worth the consideration.
The M&P is not a "Rebranded Sigma". 427 Cobra and I tend to agree on things, but this is a different weapon. The grip is very natural and probably the best of all with the exception of the P30 from HK. It points well for me, and the recoil is very soft. They definitely have the "compact" down pat. It is a nice weapon, but I wanted something that would do well at the range and CCW. The grip can be extended for the compact, but it was not for me. As a dedicated carry piece it is awesome. The M&P full size is a great range gun, but is too big to conceal effectively.
Lastly, the Glock. I HATED the previous iterations of this weapon. The grips were always a touch too big for me. I shot a Gen 4 Glock 19 and fell in love. With no back straps installed, it is the PERFECT fit. I just finished a range session with both it and my 1911 and had ZERO issues switching between the two. In general, many people have perceived problems switching from the grip angle of the 1911 to that of the Glock. The fit and finish is great. On par with the M&P and maybe marginally behind that of HK. However, the service and simplicity of the pistol make up for any perceived shortcomings. I shoot it very well, it is the perfect size for carry and the range, it is simple to work on, and has tons of aftermarket support. I foresee myself having it for quite a long time.
This is a very personal decision. You should go to your local range and rent all of the pistols you are interested in. Put a box of ammo through them and do an honest assessment. Get the one you want and can hit with. However, don't let price be the driver. That is the last way to go about purchasing firearms. Get something you can trust your life to if it ever comes to that. If it is the cheapest, great - if not, that's fine. It's YOUR purchase, designed to fit YOU.
For me, the Glock is awesome (tough to say that after trying to hate Glock and love HK). I do see an M&P full size in my future. They are both quality weapons. I personally can't justify the premium of HK any longer. You WILL pay for the name. The XD is alright, but there are better options. The Glock and M&P have lower barrel axes that allow you to control the pistol better. If asthetics are important, I think the Glock and M&P look far better than the XD.
My .02
ETA: I do agree with 427 that you should get a 9mm. The current generation of hollowpoint ammo will put down any bad guy with decent shot placement. The 9 is less expensive to shoot which means more training. It also has less snap which should equate to better quality fundamentals and ability to put more rounds downrange in a session. It really gives up very little to the 40 with the current quality of projectiles such as Corbon's DPX (barne's bullet), Winchester Ranger, and Winchester's PDX1. The Federal hydrashok is an outdate design. I recommend the previous 3 over the hydrashok.
Josh