The best AV is your brain. I haven't used an AV for years and been perfectly fine. All you really need to do is be careful what you download and not be stupid. It also helps to have a good reliable firewall in place that blocks ALL connections in and out unless you choose to accept them. Then if you download a keylogger it can't send your login details back home. AVs just use up too much resources for me to find them worthwhile.
I use Kaspersky. I havent had any issues for the past few years that I have been using it. Its very efficient and does not really slow down my PC.
Any antivirus which provides moderate security for free is best, rest you've to take care yourself. I've been using avg free for years and have no problems till date.
For me Avast Home edition is the best one. It is a full version Antivirus which is offered free. I have been using it since last 4 years without any problems. So Avast is the best Anti Virus.
AVG and kesper is best Anti virus but both should be registered crack version . otherwise trail versions cannot be more powerful then registered one.