I don't use Ad Aware any longer, but having said that I still use Spywareblaster, and occasionally run Spybot as a check. I think Spyware Terminator is an excellent program particularly as it also gives real time protection.
You say that AVG AntiSpyware finds dozens - what is the nature of what it finds (especially as, from what you say, the others apps don't find them)?
Amongst others, I use Trend Micro Housecall. It finds a few things that I have on my system that it considers suspect (and I can see why) but are genuine apps - such as Snadboys Revelation and Magic Jellybean. It even detects that I don't have certain Office security updates installed.