Use the free built-in antivirus called Windows Defender? Use a free tool like Avast? Buy a third party tool?
The situation is an interesting one. Redmond is walking a tightrope here. On the one hand they do not want to tick off their third party security partners, and on the other hand they do not want to have millions of users unprotected that do not want to/can put AV on their machines for a variety of reasons.
So, what I seem to observe here is that they make both sides (AV vendors and users) "moderately unhappy" as a compromise, but in the mean time provide a very efficient AV engine that protects against what is -really- out there now. Kind of like Audi under-reporting the amount of horsepower in some of their high-end cars.
Here is what Holly Stewart, a senior program manager of the Microsoft Malware Protection Center, told Dennis Technology Labs that Security Essentials -- by design -- will "always be on the bottom" of antivirus software rankings.
The reason, per Stewart, is that in 2011 Microsoft decided it didn't make sense to fixate on developing the best antivirus software in the industry -- which at times relies on effectively gaming third-party tests that don't necessarily reflect real-world threats. (Having been inside the AV business, this is actually true).
The company shifted toward focusing on "prevalent threats," Stewart said. "We developed this new telemetry to look for emerging threats -- sort of an early notification system that new threats were emerging. We had this group of folks start focusing on those threats and we saw that it increased our protection service level for our customers. We're providing all of that data and information to our partners so they can do at least as well as we are," Stewart said. "The natural progression is that we will always be on the bottom of these tests. And honestly, if we are doing our job correctly, that's what will happen." Stewart said Microsoft was "doing everything we can to protect against real threats" and passing data on those threats to antivirus makers, so multiple parties can target the problems.
So, my take on this question is that the best free AV for Win8 is Windows Defender (and I am running it on my home and office PC now) BUT, AV IS NOT ENOUGH.... so I am also running the beta of our coming whitelisting product in tandem with Redmond's protection, and the combination of the two have not let me down yet. Want to participate in the Beta? Fill out the survey at the bottom of this page: