IMO Kaspersky is unbeatable. Real Time monitoring & protection along with network intrusion detection.
It's scan engines are efficient enough to determine most of the ZERO day attacks based on behaviour and signature.
I have used around 7 well known antivirus programs including bitdefender, norton, avast, avira, quickheal, eset & Kaspersky.
But it's been 5 years, I didn't switch to any other program after that. You can say Kaspersky is that good!
Of course you'll have to check if your machine architecture and specifications allow it since it's pretty heavy but hey, anything that's light gotta have some loopholes or missing functions in it. Not sure of the price comparison though since I didn't check the others. You gotta spend some to save some!