AVG is a great antivirus program. I would recommend it over avast in a heartbeat. It is easy to understand and is user friendly. Not in the 5 years i have used it have i ever gotten a virus or any other infection on any of my pcs. I regularly once a week run the in depth online panda scan to double check the computer. I have heard people who have used avast in the past and have had viruses get past the security.
I don't use antivirus software, and I haven't had a virus in about 7 years.
(if you're wondering how I know, my friend checks it with NOD32 and Kaspersky every once in a while, believing he'll actually find something so he can gloat.)
It's not about what you use, it's about your knowledge of a computer.
If you're talking about the best, then NOD32 kicks both their asses, but that's neither here nor there.
As for AVG, if you go on a dozen people's PCs with AVG, and run NOD32 or any other GOOD antiviral software, you will not only find stray viruses, but you'll find that AVG's .exe is infected with a virus, and that virus has spread through the computer as well. There are over a dozen viruses that attack AVG specifically, and the protection against its own infection is pitiful.
I've worked in computer repair shops and have seen it first hand. AVG is a POS.