S&W M&P vs Glock

S&W M&P vs Glock
See also http://jumpthestack.blogspot.com/2009/10/glock-vs-springfield-xd.html

M&P pros:
- Arguably more ergonomically contoured grip and adjustable backstraps (the gen 4 Glocks have adjustable backstraps.  I haven't held one so I don't know how it feels, but I don't like the feel of the older Glocks)
- Can be field stripped without dry firing
- Comes with steel sights vs Glock's plastic sights
- Traditional rifling means you can shoot lead bullets through it, as opposed to the Glock's polygonal rifling
- Ambidextrous slide release
- Beavertail grip prevents hand bite.
- Traditional 1911 style grip angle provides similar feel to other guns

- Smith and Wesson is an American based company if that matters

Glock pros:
- Magazines less expensive
- Greater availability of spare factory or aftermarket parts / holsters
- Longer track record of service
- Shorter, more positive trigger reset (The Apex RAM for the M&P is an aftermarket part that can improve the M&P in this regard).
- Pisses off anti-gunners more
- Glocks are easier to detail strip.  A complete detail strip can be done with just a Glock disassembly tool or equivalent punch.  The M&P requires taking the rear sight off to get at the striker block, and then once you do, there's a spring loaded plate covering it which is easily lost.  The M&P also has an easily lost spring loaded detent under the sear, and an easily lost takedown lever retaining wire connected(but not secured) to the sear block, and on non-thumb safety, non-ILS models there is an easily lost little plastic circle that covers the hole where the thumb safety or ILS would go, and which is not secured when the sear housing block is out.

Arguable:
The M&P is available with an ambi thumb safety on some models.
The M&P comes with a magazine disconnect on most models, which some people may or may not like, but it's easily removable.
The M&P is more likely to auto-forward often when you slam a mag in while the slide is locked back.  If you get the technique right, it will do it every time.  This may or may not be desirable depending on preference.

Glock vs Springfield XD

This debate has been done to death, but I'll give my thoughts.

Glock pros:
Better reputation for durable finish and reliability.  Note: The XD has been through some torture tests as well and is considered very durable and reliable as well.  The pre-2006 XDs used an inferior "Bruniral" finish, but now uses Melonite which is basically the same as the Glock's Tenifer finish.
Glock has a wider availability of aftermarket parts including holsters, sights, etc.  It's generally harder to find parts for the XD, as well as gunsmiths who know how to fix them, and most people probably just send it back to Springfield if something needs fixing.
Glocks generally weigh less than comparable XDs.
The Glock has a quite shorter trigger reset which means it's easier to shoot rapidly.  Note: The XD-M has a much improved trigger reset which is supposedly even shorter than the Glock's.  I haven't tried it yet.

XD pros:
It comes with a mag pouch, crappy holster and mag loading tool.  The holster and loading tool are pretty useless.  I found the holster to have way too tight retention even when the retention screw was totally backed out.  The loading tool was awkward to use and much slower than loading by hand or using the Uplula.  The mag pouch is okay, although the fact that it holds the mags in a V shape is ergonomically weird and probably not optimal.
The XD has a fully supported chamber, which means it's less likely to have a "kaboom" type issue, especially with overly hot reloads.  On the other hand, the Glock's less supported chamber supposedly reduces the chance of feeding failures.
The XD's barrel has traditional rifling, while the Glock's has polygonal rifling.  Shooting unjacketed lead bullets through a stock Glock barrel isn't recommended.
The XD comes with metal sights, while the Glock comes with plastic, less durable sights.   Note this doesn't apply if you are going to get night sights on your Glock anyways because the night sights are metal.   The XD uses metal magazines while the Glock uses plastic mags.  I don't think it necessarily matters but some might say the metal mags are more durable and more likely to drop free. 
The XD has a 1911-style grip angle, which many shooters prefer.
The XD grip is considered more comfortable by most people, including me.  The Glock grip is a bit wider and blockier.
The XD's trigger is a little crisper and less mushy.

The XD has a significant downside: the XD's slide can only be pulled back while the grip safety is depressed.  That means that certain one handed malfunction clearing maneuvers may be made more difficult.   It also means that if the grip safety mechanism breaks, there's a chance that the gun could be totally locked up, possibly with a live round in the chamber.

Debatable:
The XD has a grip safety, which some people like and some don't.  I like the grip safety in concept, but the issues mentioned above regarding pulling the slide back make the XD's implementation of the grip safety very unattractive, unlike on the 1911, where you can pull the slide back without depressing the grip safety.
The XD has a loaded chamber indicator and cocking indicator.   Note: Newer Glocks also have a LCI, and you can tell if it's cocked because the trigger is to the rear.
Both companies generally have excellent customer service.  I believe the Glock warranty is one year, but they will generally fix your gun for free at any time.  The XD's warranty is lifetime.  I believe neither company cares if you're the original buyer.

Note:
The XD-M, Ruger SR-9, and S&W M&P are all somewhat newer designs in the same class that are worth considering.  For example, they all have adjustable backstraps and none of them require dry firing to field strip.  I'm not very familiar with them, so we'll leave it at that.