Security Essentials tbh, it is one of the quietest ones I know of that does antivirus scanning and that's it.
The rest of them have all turned into bloatware or don't work (Norton) i used to recommend bit defender as well all the time, but that has gotten top heavy as well now.
@Baggy Please don't recommend Norton
Ever again, that tech "advice" was painful to read for everybody involved.
If your on Win10 your probably already protected.