Hello!
"Best" is somewhat objective and really depends on what type of information you're seeking. You mentioned that you don't use AutoSupport, but even without sending the information to NetApp you could still have it delivered just to yourself.
There's a large number of products which do monitoring/reporting on NetApp storage. In our own portfolio both OnCommand Insight and OnCommand Unified Manager will generate reports about many different aspects of the systems. Additionally, again depending on the information you desire and your palate for internal development, something as simple as the NetApp PowerShell Toolkit (or any other language which has an SDK such as Perl, Python, Java, etc.) can be used to query, format, and present reports.
Leaving the NetApp family there is a bevy of products both open source and propietary from our partners and the community...it really depends on what features, functions, and details you want to report on.
Hope that helps.
Andrew
If this post resolved your issue, please help others by selecting ACCEPT AS SOLUTION or adding a KUDO.