I've heard good things about all those mentioned so far.Remember any anti virus program is as good as its last update.Perhaps this is why different tests come up with different winners.
What you don't do is to run two antivirus programs at the same time.That causes many incompatibility problems.
Above all though , surf sensibly.Don't open attachments from untrusted sources.Don't use Internet Explorer as most viruses are targeted on it and MS is slow to provide fixes.