I will personally give more points to Kaspersky, but 6 months ago, a worm "win32,Zlob.b" attacked, when kaspersky detected, but could not delete it. i had tried 10-15 times, it got deleted, but again came after restart, this went for 2 days, and then i tried Nod32, and it was gone. So no antivirus is "the best."
Preferable ones are:-
For low resource - go for Nod32
medium to high end Computers - Kaspersky.
Do not go for avast, though it is free and skinnable, a free stuff can never beat a paid software, a can bet. By the way, do you want appealing look or protection and peace of mind?
BitDiffender is a good choice with built in antispyware, but it is heavy on resource, so also norton. I will never never recommend norton, because while burning a dvd, it started to scan the accessed files and the dvd was fried.
lastly, kaspersky gives best value for money, i think.