I personally use ESET for my Windows install. I think it's good enough IMO.
eset ,kaspersky or bitdefender.
The last one is the cheapest of the bunch.
In my experience, Bitdefender tends to slow down my PC by a lot. Though I haven't used Bitdefender in several years now.
Windows Defender + common sense (like download from trusted sources only, don't click on shady links or visit shady websites - use ad blocker, helps)
I have been using it for almost 2 years now after using Bitdefender earlier. I stopped using BitDefender because of false positives.
Newer versions of bitdefender AV (not internet security) are not that resource intensive-i am using it on a pc with 4th gen i5 and 8gb ram and its working fine,although it has some odd quirks which may annoy some.
I should probably do that. These "internet security" apps seem overkill these days. I'll probably downgrade to a vanilla anti-virus edition next.