Admittedly, I haven't used AVG for years. It could easily have been improved since my last experiences with it. But for the hell of it, I'll describe the experience that got me to stop using it. Through a download, I ended up getting a virus on my computer. Awesomely, I was aware of this before AVG noticed anything amiss. 20 some programs with names like r1.exe suddenly installing themselves to your computer can be a good hint. Especially when deleting them causes them to be reinstalled again within seconds, your startup list starts having programs added to it, and the amount of processes you have running roughly doubles.
AVG is like "virus detected, please scan to get rid of it".
It's worth noting that I quickly made sure I had the newest virus database they'd released, just before pulling my net connection so as to be able to scan without anything new adding itself.
A little later, AVG claimed my computer was completely clean. Yet I still had processes running that shouldn't have been, files that should have been quarantined that it never noticed.. and upon plugging back into the net, the virus resumed where it left off.
Alternately, one day a friend recommended Avast! to me. Shortly after installing it, I decided to test it out by attempting to download and install a (non-virus) keylogger to my computer.. intentionally.
Avast! popped up a warning as soon as I clicked the link to download it, telling me that it didn't think I wanted to do that.. another when the download finished, telling me that the .DLLs in the archive included a number of virus-like hooks (afterall, it was a keylogger), and after overriding those and installing the program anyway, Avast! continued to complain about it.
What impressed me most about that was that it was complaining about the process, what the program was doing in active memory, and such at that point... not even just the physical set of files.
Comparitively, it probably goes without saying that I feel far safer with Avast! than AVG.
And Ad-Aware is certainly nice in terms of getting rid of spyware.
-------
Unbelievably awesomesauce to the absurd degree that I wet myself.
Who else has created a LW/magnets
so explicit the mods deleted a screencap of it? =P