They are all nice firearms. High quality, popular and top of the line.
Here's my take for what it's worth.
Glock: The ugliest of the 3 choices. However I love Glocks, and of the three choices, would be mine. Lowest bore axis of the 3 = less muzzle flip = less "felt" recoil and should be quicker on target. Also has a very short trigger reset.
Polygonal rifling: "A number of advantages are claimed by the supporters of polygonal rifling.
These include: Not compromising the barrel's thickness in the area of each groove as with traditional rifling. Providing a better gas seal around the projectile as polygonal bores tend to have a slightly smaller bore area, which translates into more efficient use of the combustion gases trapped behind the bullet, slightly greater (consistency in) muzzle velocities and slightly increased accuracy.
Less bullet deformation, resulting in reduced drag on the bullet when traveling through the barrel which helps to increase muzzle velocity. Less sensitive to stress concentration induced barrel failure. Prolonged barrel life."
The down side of Poly rifling is they may, or may not, build up with lead (depending on who you are talking to).
This is fact though. Glock does not recommend shooting lead through their Poly rifling. Also the chamber is unsupported, so shooting reloads is also frowned upon. (It may be possible to split brass that is weaker, as it has already expanded and thinned from being shot at least once already.)
There is a reason Glocks sell as well as they do. They are reliable, accurate and practically indestructible.
Springfield XD. Another great pistol. Similar to the Glock in its build. Different ergonomics. Squeeze safety. Traditional rifling. I have nothing bad to say about a gun that has become as popular as it has. Feels good in the hands and shoots well.
Beretta 92. The best looking of the 3 choices. Feels great in the hand, and shoots good. Traditional rifling. They had major issues with the locking blocks for many years, to the point Beretta recommended the barrel be inspected, if not replaced, around 7,000 rounds. They have made improvements, and unless you are pumping hundreds of rounds through her weekly, you should have no problems.
At the end of the day, you should get what you like and are comfortable with. Some shooters MUST have an external safety. Some are fine with internal safeties. Some need a visible hammer. Some are fine with strikers.
If you have a range that offers rentals, I would take them up on trying the 3 out, by sending lead (or plated lead) down range. You will easily find out what you like, or dislike by spending a little time, and a little dime on the research.
Good luck on your purchase.
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