Best is subjective and depends on the users requirements, best at what, e.g. detections, light on resources, etc. etc. I like the Repair function in SAS, which isn't in any of the others.
There are aspects I don't like so much in some anti-malware applications which regardless of their apparent strengths would rule it out, but my likes and dislikes are likely to differ with other users, hence the comment best is subjective.
One thing for sure I wouldn't give hard disk space to adaware nor spyware terminator.
There is also nothing to stop you having more than one, so long as only one of them is resident and the other on-demand.
SpywareBlaster, shouldn't be on the list as it isn't an anti-malware, being neither resident or on-demand, it isn't looking for malware but adding settings to IE and Firefox, etc. to block known malicious sites, etc.
