I don't like the alternatives to antiviruses as I find them to be too intrusive. I like that AV software will only ever prompt me if an infection is found (or a false positive), or possibly if it finds some suspicious activity. I install new software just about every day, and using other security software causes one or two problems for me. The first one is lots of prompts to allow or deny things. I find this to highly annoying, and for this reason I have UAC disabled as well. This would not be an issue if I rarely made changes to my system. However I have hundreds of programs install, and install new software just about every day. The second problem is that in order to run or install some software I would need to manually setup whitelists. With antivirus software, I can do pretty much whatever I want on my system with no prompting or blocking.
I was running HitmanPro.Alert briefly, but soon removed it as it was blocking too many things and I did not want to have to manually add exceptions. Also, I was running VoodooShield for a few months. I stopped using it as I was getting tired of the popups, and the delay of a few seconds when lanuching an installer while it scanned it.
I don't use Windows Defender as I've found that unless you have a very fast CPU, it can cause very noticable slowdowns at times. I've witnessed this behaviour on many computers. I use an antivirus which has an absolute minimum system impact - IObit Malware Fighter 4 Pro, as I don't want my laptop to ever run slowly if I can help it. I have seen a post on another forum where someone said Windows Defender was using less CPU time under Windows 10 Anniversary Update than the previous build. I have not tested this myself yet.