Glock is known for reliability and the 9 mm Glocks will fire almost any brass round you put in it. Like car brands and favorite oil brand, some prefer Glock, Sig or other brands but you definitely want to stay away from price only brands. As others have said, you
need to get the gun in you hands and see if you feel comfortable with it. Some ranges have guns you can rent for the hour to try out different brands or types. Either that of find a "gun nut" who one of everything and get an "edjumacation".
As far as Glock goes:
The G17 is a full size 9 mm and you can practice with 115 grain target rounds and use JHP +p rounds for defense. The G19 is the same gun with a slightly shorter barrel but still reasonably sized. You can also get a conversion kit so the same gun will shoot .22LR. Great for low cost practice and plinking. The nice thing about shooting .22LR with the same weapon is that you have muscle memory and will feel more at home. For just a little more than the cost of the conversion kit you can get a G44: the G19 size but shoots .22LR. Now you have two complete guns.
One more thing: Concealed Carry will dictate what size gun you get since a heavy gun is hard to carry and a long barrel is a hard thing to draw. There is a great quiz at
https://us.glock.com/en Entitled "Which Glock is right for me"
You don't want to cheap out on your weapon. Spend a little more and have the best. You won't regret it.