You might want to wonder about other things, but lets not worry about them. Lets assume that your range of choices are all made by reputable manufacturers and each gun has an excellent reputation. Lets also say that the purchase prices or both guns are the same, both have same level of complexity when disassembling, and ammunition is also readily available for either as well.
What is left? Physical size and the measure of its power. The most easily concealable gun is not going to be the most powerful. The most powerful will not be the most easily concealable. You have to find the middle ground that works for you.
You should always test out http://showtimegunsammosales.com/ a new gun before you buy it. Before buying your first gun you need to try five to ten guns so you know what you like and what you are comfortable with. Many gun dealers with shooting ranges have a variety of guns (often their best selling models) that you can demo for 30 minutes or an hour for a small fee (sometimes just for buying ammunition).
Many so called gun “experts” will roll their eyes if you tell them you carry a .22. These “experts” will say it has no stopping power. This is pure arrogance. If you shoot a bad guy with a .22 I am pretty sure he will immediately begin leaving you alone. If not, one of the ten more going his way way should do the trick. If a .22 is what you are comfortable carrying, then by all means, carry that. It is far better to carry a .22 than nothing at all.
Research is key. The more sources, the better. If you search Google for “Glock 23 review” you will get more than 1.5 million results. Are they all reviews? Of course not – but enough are for you to get an idea about the gun. Youtube is also a great resource for getting information about a gun. For the same search term there were more than 3,700 videos.