After using many anti virus this year, I came to conclusion that Avast Antivirus is pretty good.
1) Real Time Shield (Common in all antivirus)
2) Web Shield (Common in all antivirus)
3) Link Scanner (New)
4) Browser Cleanup (New)
The last feature is most useful feature. It removes the spam toolbars from all your browsers which I find most useful.
After using for few weeks, I’m satisfied with avast.
Download avast from here: Avast Website Link