I think most reviewers are not antivirus specialist so sometimes they don't really know what they're talk about. For example, they say AVG Free has auto update feature but in fact, AVG Free has no real auto update feature at all.
In my opinion, at the first glance, AVG Free looks good & promising than avast! Home Edition, AVG Free has plain interface that looks more professional than default skin of avast! Home Edition. Otherwise, I think AVG is more popular, more recognized brand than avast! (or even more recognized than NOD32, Kaspersky, Panda, Sophos), when people think about free antivirus so AVG comes first.
If I'm not wrong, I think AVG Free is the first free antivirus available for home users and AVAST32, AntiVir or CA InoculateIT came second.