None at all, they’re useless anyway. It’s not that hard not to get infected in the first place – just don’t click on email attachments, use a browser with no known vulnerabilities and generally don’t execute shady stuff.
And when a virus scanner does discover a virus in your system, it’s too late to act. You have been compromised, the virus may have installed other undisclosed malware and/or backdoors, and you’re better off reinstalling.
Antivirus programs are snake oil.
