I'm only using Microsoft Security Essentials.
This!
I never use any kind of antivirus, except for removal.
In the last 22 years, I have had only 2 viruses, one in 2008, one in 2012, both due to my own stupidity.
2008: I used Internet Explorer for a torrent search. <-- A STUPID THING TO DO!
2012: I downloaded a shady bitcoin-mining screen saver. <-- A STUPID THING TO DO!
So in my conclusion, there's nothing like common-sense, that's the best antivirus!!!
And for dangerous stuff, I just use Sandboxie or a Virtual Machine.