My vote goes goes to avast, i am using it since 2 years and found it fast, user friendly, shields are more accurate and also auto scan of every file before executing it. I used Eset, kaspersky, AVG, norton and McAfee but still my favorite is Avast.
I used to use Avast, Avira back in days. and one of my friend bought 'one' kaspersky license key BUT it turned out to be a '3' key license (3 keys license for the price of 1 key licence)
So right now, I'm using Kaspersky.