I think in terms of Antivirus Software there is a top few, AVG, Kaspersky, Avast and NOD32. These names are always popping up. I think we can safely assume Norton is cr*p lol. But in terms of which one is best, I think the top few perform equally to an extent and its just personal choice in terms of ease of use, system resource, GUI and so on.
Personally I prefer Avast as I've been using it a while and got used to it. Also, it hasnt given me any problems.