I used AVG for a long time, but after some combination of updates and changes on my PC, I went through a period where some part of AVG kept eating up all my RAM. No matter what I did to try to reconfigure it, I couldn't get past this problem, and soon discovered that others had had the same problem, so I got rid of it.
I've been using PCTools since then, but did get attacked recently and had to install MalWareBytes to clean it up. After MWB was done, however, I ran PCTools again, and it still found some traces of the problem. Maybe using multiple tools is the only hope!
--Maria