Pure Scrum tool

I have researched various Agile tools:  VersionOne, JIRA Agile, Rally, Axosoft, etc

Most of these products seem to use Agile (some use iterations instead of sprints), but for the most part they do not seem to be Scrum specific.  I suspect Axosoft may be an exception, but I have  not been able to look at it yet.

In the opinion of the experts on this board, which of these tools or other Scrum or Agile tools provide the 'most pure' Scrum view (as opposed to a general Agile).

Thanks