[--From My own experience since i have used all Kaspersky / Eset Smart security /Bitdefender -- ]
Eset Or Bitdefender Thamai hondama :)
Kaspersky nam pc ekata daannawath epa .. Virus guard ekak patten KIS uparimai .. but PC eke anith weda serama slow wenawa ,
Shortly KIS 2010 (KIS7 was good)...