They are all actually about the same. There is no AV product that will block 100% of viruses. The key to protecting your computer is to apply layers of security.
1) install an AV client
2) ensure you keep up with the latest OS and application patches
3) scan your computer regularly with a different anti-malware product such as Malwarebytes and/or Hitman Pro
4) use a web filter such as K9 to protect you from sites that are categoried as having known malware
5) use a smart screen filtering plug in in your browser to get alerted when reputable sites are found to be hacked and reported as having malware embedded.
6) dont open click on links in email from people you don't know or look suspicious
7) never give out personal information, usernames, passwords, identify to unsolicited email.
Following these best practices will ensure that you stay protected
I don't really believe there is a "Best" AV program out there. It's all about who updates their virus definitions most often. I personally use Microsoft Security Essentials because it's free and have had no problems using it for over a year now. I used to have Norton, but found it absurd having to pay for it when there are free ones in the internet.