None of the above. I use Advanced SystemCare Ultimate. But, I have used all of the above antiviruses under Windows 10 at some point.
None of the above for me either, Defender I find works great on Win10 coupled with MBAM Premium and Adguard.
Why adding a free AV on win10; when you have already a pretty good one built-in, that is OS-aware and work more on prevalence; if you are not confident in it , just add an anti-exe. realtime 3rd party AVs are pointless now; their signature model is based from the prehistoric age of computer security, are way to much subject to FPs, and impact your system like a elephant walking in a glass shop.
@guest Unless you have a really fast computer, it can cause very noticable slowdowns. It seems to run fine on an i7 laptop, but not so well on anything less in my experience. On my Core 2 Duo laptop which I use daily, it made my computer run a lot slower.
I have similar experience. WD has bigger impact on system performance than some 3rd party Avs (using it on netbook).
@guest Yes, that's true too. Actually I never take too much notice of RAM usage unless a security product is using many hundreds of megabytes of RAM. Quite suprisingly over the years I have seen one or two antiviruses which caused high CPU use without slowing down my computer.
I have tried all free AVs and I install Bitdefender Free, it runs light and fast on 10. My second choice would be 360 Essential, no other good free AV.
You should rename "Windows" to "Windows Defender" for the sake of clarity. Not everyone will assume it means Defender.
I was using avira free + web guard for my friend's laptop but she had extremely high ram usage (1.4gb) after playing a game for an hour so I had to install avast free + transient caching disabled (which I think I have the best performance and least disk i/o usage) no idea if avira has fixed this memory issue or not after update 17 but in normal conditions, avast still uses less memory than avira
On some systems MsMpEng.exe can cause 100% CPU-Usage. After exluding MsMpEng.exe, CPU-Usage is back to normal.
MSE or Windows defender depending on the version of Windows. The days of signature based scanning being more than a auxiliary approach to security are long past and I just want something free and minimal.
Fix High CPU Usage & Performance of Microsoft Security Essentials and Windows Defender (by tweaking.com)