If you know what you're doing I'd say no AV is better than the false sense of security an AV provides. Of course you can end up thinking you know what you're doing and later find you didn't.

Don't run browsers on OS accounts with anything but the most basic rights. Use NoScript to block all javascript except the ones you really need. Run an adblocker. Scan any remotely questionable downloads with https://www.virustotal.com/ (after all, 70 AVs are better than one). And the hardest to define: employ common sense and be skeptical of everything that doesn't feel right. Above all: backups and backups of backups.

You're probably fine without one unless you're completely technologically illiterate and visiting shifty sites.