No-brainer Mac imaging tool?

What would be your tool of choice if you want to get the most accurate disk image suitable for analysis on a different computer (encryption stripped)? Imagine you do not have any commercial tools at hand, so you need to justify any new purchase. It would be perfect if the tool could preserve as many low-level filesystem artifacts as possible (otherwise I could just dmg/tar/rsync it, right?). aff4 would be a plus, but not a requirement.

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