Norton Anti Virus is the best.

Bitdefender in my opinion.

I like webroot at the moment

I do not use an anti-virus on my development machine (I know, I know). It tends to slow the system down and has caused some headaches in the past.
For home/non-work computer, I have been using Avast for several years and have been happy with it for the most part.

In the end, if people would slow down and read things before they click (I am talking to you mom and dad)...

- Taint McTaintness

Eset! Never let me down!

Avast, the free version without the extra tools...its a lot faster then the paid version, at least from my tests
and seems more reliable then most other paid/free things out there.
Avira would be my second choice.I'd stay away from AVG.
Sadly no antivirus is failsafe.

For me, Norton Antivirus was the best until my subscription was over. Moved to ESET Antivirus which was also good, eat less of your memory. Bitdefender antivirus also a good option. However, lately moved to Symantec Endpoint Protection v. 12, which I feel is the best among all.

Kaspersky AND AVG...

Baidu

Kaspersky was slowing down my computer a lot, so I moved to BitDefender and is great, but I miss Kaspersky's firewall settings.