I'm using Eset NOD32.
In the past, I have used AntiVir, avast!, Bitdefender, eTrust, F-Prot, Sophos, Trend Micro, AVG, Panda, Norton, Symantec Antiv?rus Corporate, Kaspersky... I have used all principal antivirus softwares.
I like Kaspersky and NOD32, but I'm using Windows Server 2003 and Kaspersky don't install in Windows Server versions.