The problem i find with asking people which is the best they will tell you the one that uses the least resources and causes them the least issues. However your getting the information that matters and that which protects you the best.
http://www.virusbtn.com/vb100/archive/2008/10
The above site gives that information but you will need to register
last time i looked (over a year ago) ESET was the best but i dont think thats the cases now