I'd suggest that you go through a process of elimination that goes something like this:
1. Rifle or Handgun
2. If Rifle, what caliber; if handgun, what caliber
3. Then, consider what type of action you want - semi-auto, bolt, single shot, lever; in handguns, there are about 4 semi-auto actions and about 2 revolver types to choose from.
4. Price range; Used or New.
5. Then you can get into brand, and materials like steel & wood vs. alloy and poly.
It's sort of like saying - OK, I want to buy a vehicle, what should I get? Well, I might suggest a 32" sail boat. You've got to at least eliminate everything you are not interested in and set some parameters to get useful suggestions.