There are a lot of anti virus available in the market. But in my point of view followings are the best top 10 anti virus.
1-Comodo Antivirus 2012.
2-Avast! Pro Antivirus 2012.
3-BitDefender.
4-Panda Antivirus.
5-PC Antivirus Pro 2012.
6-Kaspersky Anti-Virus .
7-Norton Internet Security 2012.
8-AVG Anti-Virus 2012.
9-pyware Doctor with Antivirus.
10-Avira AntiVir Premium.

I thought bitdefender was the best.. yea I just checked, lot of ratings actually show that bitdefender is at the top.. I don’t know