Gotta recommend eset. Been using smart security for 3years without a hiccup. Steer well clear of macaffee, and Norton. Both caused me lots of problems in the past. I dropped avg for eset due to bloat. It was a much heavier install and used more resources to update, but if you're going free I had no major issues with avg. Sent from Bittech Android app
Avast for the gaming mode and excellent detection rate. Edit. Why all the love for MSE when it still scores lower than Avira and Avast in detection and false positives?
Personal experience: AVG let me down in a big way. Kaspersky internet security is fully featured, includes an excellent firewall, and is free when you use the online banking service from one of the uk banks. It is a little heavy to use for less powerful machines though, and slows down backups and file transfers on networked drives even on powerful machines. My AntiVirus solution of choice is MSE, complimented by Malwarebytes scans run on a regular basis and on untrusted downloads. Run a fully patched Windows and don't trust anything that you haven't heard of to run on your machine without researching(Google it!) first.
After using quite a few different ones over the years i prefer Nod 32 nowadays, i can tell it to completely leave my game folders alone, and its easy to use