Welcome to the forum!
At the outset, I'll say that as a new handgunner, you might consider some guns that recoil less than a lightweight .45, and also some calibers that are less expensive to shoot. But if you are set on the .45, here's my take on the guns you mentioned.
Glock. Excellent and deep track record for reliability. Low bore axis and short trigger reset, subtleties often unrecognized by new shooters that make guns easier to shoot well when accuracy is weighed against speed. VERY big grip, really only suited to shooters with very big hands. Holsters, magazines and accessories very widely available.
Springfield XD. Excellent reputation for reliability. Has some safety features that some people, especially newer shooters, like. Grip more comfortable than the Glock for most people. Bore axis is fairly high and trigger reset somewhat long. Holsters, magazines and accessories fairly common.
S&W M&P. Bore axis and trigger reset better than XD. Interchangeable backstraps to customize fit to hand size. Seems reliable thus far, but not too many guns in the field yet, compared to Glock and XD. Accessories probably harder to find.
Springfield 1911. Superior ergonomics, with low bore axis, potentially excellent trigger, and small grip. Best carried cocked with safety engaged, which requires more training than the "point and pull" guns above. As with all 1911s, reliability is something of a crapshoot, especially when shooting modern hollowpoint ammo. Holsters, magazines and accessories are everywhere.I have the Crimson Trace grips on two of my three Glocks. I won't be getting one for the third. The CT Glock unit, while mechanically very well designed, makes an already big grip even bigger, while the housing for the laser diode barks my thumb knuckle in weak-hand shooting. These problems may be due to peculiarities in my particular hand size/shape, but you should probably try one live-fire before you spend the money.I am leaning toward the glock 21 actually at this point, basically for it's simplicity and the fact that price wise I can buy the gun and slap a crimson trace laser on it and still be cheaper than the particular 1911 model I like(which is my second choice at this point).It really depends on how experienced a shooter you are. When I evaluate a pistol on the range, I observe four things:So what should I be paying atttention to as I shot these guns.
1. My group size.
2. How high the front sight flips during recoil.
3. How quickly I can reset the trigger.
4. My speed between shots (called "splits"), as measured with a shot timer, if one is available.
I personally don't get too hung up on "feel." As long as you can reach the trigger and get enough hand on the gun to manage the recoil, your hand will likely adapt to almost any variation in grip shape. This is one big reason not to completely rely on subjective impressions of "feel" when fondling guns at the dealer, but rather to shoot them and see how they compare objectively in terms of accuracy and speed.