WannaCry wasn’t really a zero day exploit IMO since it was a known and fixed issue. What the NSA would’ve done (or has done) with it would’ve been (is) one.
And back on topic: I’m also all the way Windows Defender and being careful. Never had a virus since I had my own PCs. I used some other antivirus software (Avira, Norton, avast, iirc) back in the days just because I was used to do that since '95, 2000, XP, etc., but after not needing them and annoying me for nearly ten years I switched to just not using specific antivirus software.
I really like the topic though. Never heard of ESET tbh. Will take a look at it, I think. I’ll probably won’t buy it though since I won’t use it anyways