Are you TRYING to start WW-III, or is just an added benefit ?
Best thing is go a rent a bunch of both then find out which you shoot best and are most comfortable with.
No matter what ANY ONE recommends 3 people will say the caliber is to small, a couple more will say the gun is crap, and then some one will post that none of these people know what they are talking about the ONLY option is a (insert random brand, model, and caliber here)
For self defense I
prefer .357 Mag,revolver or 1911 in .45 acp. because
.22 isn't enough to trust your life to and those 2 calibers are the most common, (although .45 ammo costs more when you can find it) after that 9mm as it is the most common world wide. Of these 3 cartridges the newest is the .357 which dates back to the 30's, both 9mm and .45 ACP are over a 100 years old. the chances of surprises are pretty slim. Glocks are OK, the only VALID complaint is some people don't like the grip, hell with them, if you shoot it well it will grow on you like an ugly puppy, they seem to be the most indestructible brand on the market, points are awarded for going bang good looks aren't needed.
If you are looking for total concealment, something like a Kel Tec or Ruger LCR may be what you need, small size makes them difficult to shoot well but they can be carried covertly as opposed to simply concealed,
DO NOT TRUST YOUR LIFE TO ANYTHING SMALLER THAN .380 That's just some general info, there are to many variables you have not mentioned to HONESTLY be any more specific.
As I said, try as many as you can, then compromise with comfort, (you need to carry ALL the time, ESPECIALLY when you think "oh I won't need THAT") conceal ability, (How will you carry it so it does not show but is still accessible) and shootability, (does you no good if you can't hit with it) when you settle all that then there are price considerations, can you afford a $3000 custom 1911 or are you limited to a $200 Hi Point. When you get a hand gun you MUST have a holster if you intend to carry it safely. once you have decided on equipment
get professional training in SD, if you do not already know a
REPUTABLE trainer ask at your local gun store, range and Police Dept.