All depends on your local laws and what you want to do with them.
As the others have said getting your basics is what I would also recommend. A carry handgun, an AR, while some may disagree with me I think a pump action shotgun is very useful to have, and a full size handgun if you want.
For a carry gun you have many options to choose from. Glock, HK, Smith & Wesson, CZ, ect. For an AR you have even more companies to choose from Areo, BCM, and Smith & Wesson to name a few. For a pump action shotgun you have three choices: Beneli, Mossbergs, and older 870's. It also depends on how much you want to spend on the shotgun. If money is tight I would say get the 20 inch Mossberg Maverick 88. 7+1 rounds of 12 gauge will solve a lot of problems. I will caution you on keeping a pump action loaded that they are not drop safe. If you have a shell in the chamber and it falls over there is a good chance that it will go off. Don't do that. Keep it loaded "cruiser ready" hammer down on an empty chamber or snap cap if you are paranoid about dry firing you firearms. Most new firearms can be dry fired with no issues. Read the manual. A full size handgun may be redundant if you have a carry gun.
No matter what guns you choose be sure to train with them and know where your carry/ duty ammo will hit at different ranges. If you get an AR I highly recommend getting a 22LR bolt carrier conversion so you can train with you AR and not blow 50 cents a shot. CMMG sells the bolt and mags.