Over the years I have had all kinds of paying and free antivirus protection, the paying ones including Symantec and McAfee.
The last one I used was AVG 8.5 free. I have had significant problems with AVG. Every new version brought new problems. At one occasion, I even had to call specialist friends to reanimate my PC because the new version kept my machine looping at startup and thus blocked my work, and I heard that hundreds, if not thousands of people had the same experience.
That is why I hadn't installed AVG 9.0 yet : there were ample warnings on internet to wait until the program was stable.
This morning I finally decided to risk it : after 5 or 6 botched attempts I had enough : no more AVG for me.
For years now, I had heard complimentary comments concerning free Avast. I decide to risk it : installation worked at the first attempt. I now hope that the software will work too !