I suppose Avast does better than most. I haven't seen anyone come on the board crying about how Avast missed something and now their machine is all messed up. Personally, I like Avast for the email scanner, the forum support, and the lack of cost on my part for its use (home version). In addition to peer support on this board the Alwil team members are on here daily answering questions and so forth. My prior experience with AV software was in order, Norton, InoculateIT, PC-Cillin, and then Avast. I like Avast the best.
I was looking at Kapersky the other day and it seemed to be way too intensive for me.