Although there are some brands that you should probably stay away from unless you just can't afford anything else, Jimenez for example, I would rule out brand recognition in favor of fit and feel in your hand.
You need to decide a few things to determine what to purchase:
1) What caliber fits you? Things like cost, weight, and effectiveness should figure into this. Although I whole heartedly agree that a .45 will make a bigger impact than a 9mm I am sure we can also agree that packing 17 rounds of 9mm is much easier than 17 rounds of .45. Also, something I looked at in determining my choices was the availability of the ammo. 9mm and .45 are much easier to find than 10mm when ammo is scarce.
2) How are you planning to carry it and how will you use it? If you dress in a t-shirt and jeans every day you will carry differently than if you wear a suit. You may have to pick a sub-compact because of concealment issues, or a full size that has more rounds and more mass because you will be out in the field and have to worry about running into a "pack of mountain lions". Maybe you find a revolver works better for you than a semi-auto because of ease of use or lack thereof.
3) How does it fit in your hand and feel when you hold it? The best gun in the world is worthless to you if you won't carry it because it is not comfortable when you hold it. Take the time to try out guns and see how they feel for you. If you have friends that also have firearms ask if you can hold theirs. Seek out a good quality instructor, there are many on this site, to help you understand what is a good way to handle the firearm and how it should feel in your hand.
4) Understand that the first gun you buy is probably not going to be the last, nor will it be your favorite down the road. Ask most any gun owner and they will tell you they loved that first gun they bought when they first bought it and then they started to better understand how it felt and operated and started looking for something better. The "something better" process never ends, honestly. Additionally, every gun fits certain situations better than others, but no gun is best for ALL situations. I have a compact and a full size. The full size is my winter and jacket carry and the compact is my no jacket, lighter clothes carry gun.
5) What can you afford? Not everyone can start out with a $1100 gun for their first. Mine was $300 and I still have it. It is not my go to for carry, but I still have it. I have since spent more on other guns, but I still have the first... for now.
This is a process and one that never really ends. Even the best gun owners out there will tell you, if they are being totally honest, that they still haven't found that "perfect gun". Take your time and purchase what is best for you at that time.
I am sure others can add to this list and better explain what I have said here, but I hope it helps. Just remember that you still have to find a holster as well.