It should be noted that for users of Windows 10, the built in security (Windows Defender) is quite adequate, and runs about middle of the pack for effectiveness. I'm not working for Microsoft or anything, but I like my system to be lean, and Windows Defender is a core part of the operating system so it doesn't have much impact the system.
If you have sound practices (don't download programs from dark alleys, don't click on seedy links, keep your browsers and OS up to date) then you should be fine with it. And you can breath a little easier knowing that Windows 10 has decent protection right out of the box.
And if you want more, or you have bias against MS (it happens), then you can install anything. Defender will shutdown automatically when it sees another program installed. When I was the IT for a small company (many years ago, before Microsoft Security Essentials), we used Grisoft AVG, starting with the free version, and ending up with a license block and our own update server.