I always want to laugh when I read any line that says "x million people can't be wrong"
I can list a long list of stupid/wrong things that x million people think is true

Of course this is not to say that avast is a bad product, it is a fine virus scanner. I don't think it is the best of the free ones, but I have installed it at my mothers and a few other places because it can be setup at the right level that it does not stress people unduly.
That is until it times out and then demand they re-register themselves and they have no idea how to do this, something which just happened to my mother and I am not going there until christmas, so thats 2 months of her being made to panic every day by avast saying her license has expired and windows saying her computer is at risk. I bet she wont dare use the net now

For more technical people I usually choose avira personal when I can, as it has a history of being better at detection. Now that there is a bit defender free I need to test it to see how it compares.