Originally Posted by OttoVonMog
... personally I would go with an MP5SD5....
Why? Only want to shoot em twice till it jams up?
OP - As many said, go to a range that allows rentals first, if possible. All guns feel different, and you may like one over another. For instance, I prefer the feel of XDs to Glocks, and old Rugers to either. There are many quality makers to choose from, I won't waste space with a generic list. Hipoint and taurus are generally thought of as lower quality, though I have a hipoint carbine and can testify that it is a tank. Ugly as sin, but hella-reliable.
As far as caliber, it isn't just the diameter of the bullet that determines its impact. The mass varies between rounds and types of boolits make a difference. A .380 is generally and historically thought of as an "Oh Sh!t" gun or "muff pistol" (lmao) for a lady. Close quarters, when things have gone wrong. This is why many carry them as backups. Keep it hidden, whip it out, and shoot em. It is easy to shoot, but in compacts are so light they can be uncomfortable to shoot.
The 9mm is a much heavier round, having much more mass relatively. It will cause a more serious wound. This is a very effective balance of weight/firepower/overall size/ability to carry rounds. It has a moderate recoil, I find this a very easy balance of weight to recoil, making it very easy for followup shots.
The .45 is a TX Ranger deluxe, as I like to say. It is a big gun that shoots big holes, particularly with SD rounds. The mass is incredibly huge compared to the aforementioned rounds, causing a much slower boolit speed. In a 5" brl, you can just about hunt with em, they are accurate at good range. Patton carried two 1911s. They are loud and they kick, short brl in particular.
The .40 is a nice comprimise of the devastating .45 and reliable 9mm. It has less recoil than a .45, more impact than a 9mm. Carries a moderate amount of rounds. Most full size 9s will hold 15ish, .40s 12ish, .45s 10ish per mag. More well placed shots, imo, are better than fewer big boolits - to a limit.
The .357 Magnum is a micro artillary shell. It has massive mass and powder, though not the biggest diameter. Length plays a big role, just like in the 7.62x39 (AK-47), a 7.62x51 NATO (.308) and a 7.62x63 (30.06) cartridges. Same diameter, way different mass.
+1 on likely to get issued a .40
I would look at a Ruger LC9, or some other of their 9mms. I like em all, but I am biased to Ruger in general. I personally find the .380 to be inadequite physically to other rounds, although it will kill too.
My shillings, and always remember, a pistol is only for getting to your rifle