I'm using Microsoft Security Essential on both of my Windows computers, works great! However I don't download programs/games and using Sandboxie with suspicious stuff so AV is not that important for me.

Microsoft Security Essentials. But I don't download any suspicious stuff.

I use kaspersky and it grabs everything malicious

Not using antivirus software.
I don't click on suspicios links, don't download suspicios files and all that...
My AV is common sense.
One time (in last 10 years), looking for software for creating WinXP boot flash-drive all around the web i stumble upon some really nasty virus, but Acronis solved all my problems.

I think I'll consider Kaspersky

Avast for past few years, right now try Avira. Avast too heavy for my PC

This might be a little contentious, but the best AV is to not use AV at all. Instead install all untrusted software on a VM with no network device which you can restore to a clean baseline snapshot whenever it gets too infected.

The best commercial one is VMWare.

Eset smart sec

i personally like avira ,coz it doesn't delete virus without our permission ,in that way my software cracks are safe

I use Microsoft Security Essentials. I like that its already installed and pretty much useful for casual downloads.