While I don't use Windows as my daily driver, I've let Windows Defender (or whatever they call the default these days) run on my Windows installations. It works

While I don't use Windows as my daily driver, I've let Windows Defender (or whatever they call the default these days) run on my Windows installations. It works pretty good (as long as you don't, like, actively download and run shady stuff from the Internet), and very likely consumes less resources than most commercial ones out there.