I have all of the ones I mentioned above, HiJackThis is an analysis tool that you can see exactly what is running on your system, so I only use it if I have any suspicion of a background process, etc. on my system.
No one anti-spyware/adware program is likely to have every different signature/detection so it is a combination of different detection signatures. Ewido is more geared up to trojan hunting, but has a number of different functions in the suite.