I've owned Avast Free since however long ago it was when it used to shout "Caution, a virus has been detected."
It's never let me down once. Although I don't download things that look dodgy or visit dodgy sites - but when I do by accident, it's always been there to stop me. My issues with it is that it takes up a lot of resources and can degrade overall device performance slightly. Plus, it's a little overly sensitive. I tried running the Minecraft Launcher a few days back and it told me that the launcher's URL was malicious.
But, other than that - it's the best i've owned and I recommend it to everyone who asks for an Antivirus. 4/5