AVG Free Least Troublesome?

I've also noticed that AVG is rather quick to adding some non-urgent sample such as Zlob trojan than other vendors, AVG can detect many Zlob variants by signature while some antivirus such as avast! can't. But based from my experience, however, avast! will eventually detect many Zlob variants when they're executed even avast! doesn't have a signature for a particular Zlob installer.