When it comes to CCW a few factors boil it down for you to pick the weapon for you, there is NO perfect weapon for all of us..
here are a few I think should be factored into a decision...
Price- what you want to or can afford to spend... and what can you afford to practice with at least a few times per year minimum...
Size-what do you want and what are you able to carry? A 7oz .22 all the way up to a 5lb ar pistol+, it has to make sense to you, weight, concealability, maneuverability, ect...
Ability-what can you manipulate and operate efficiently and effectively, if you can shoot one handedly behind your back and robin hood a 454 casull then this may not apply to you...
Capacity-what are you comfortable with for a number and what does your local law inhibit? A 2 shot derringer is super easy to conceal but hard to shoot and only holds 2, vs a FN 57 holds a 20 but is much larger and my wife can't wrap her hand around the grip...
So the bestt thing to do is start at the top, what can you afford, then go to the dimensional size you are comfortable carrying and concealing, feel them loaded, figure out the weight, and size that works for you, then go to the range and see what you can do, practice as much as you can and your ability will get better, you may start being comfortable with a 22 but quickly move up to a 9mm with a few weeks of practice...
That will tell you the caliber and gun that works for you, join a range and poke around, most guys have no issues letting you shoot a few rounds through their gun, I have done this many times, I let a women shoot my 9mm 1911 last weekend because she is thinking about carrying a larger weapon {she carries a older .25 revolver, and hated how the 9mmm barked}...
It seems the what should I carry posts are abundant here, there is no single right answer that any one on this forum can give, I know that I like carrying my p3at, its not easy to shoot BUT the ct laser is dead on at 20ft, I am confident the 380 underwoods I have it loaded with have enough "stopping" power to neutralise human threats, but the biggest reason I carry that gun is its size, I have it on a pocket clip no holster, super light, super small, and it holds 6, when I practice with it, I can pop a moving target 6 in a row 9 times out of 10 and on the 1 out of them 10 I get a miss its 1 shot out of the 6...
SO if the 22 is what you are comfortable with carry it, on the other hand though if you are a super shot with a 9mm of the same size, it would probably be a better option... I think the smaller calibers should be an option for the women, small men, elderly that can not efficiently fire a larger unit...