Is the Gutmann method the best method?

No.

Most of the passes in the Gutmann wipe are designed to flip the bits in MFM/RLL encoded disks, which is an encoding that modern hard disks do not use.

In a followup to his paper, Gutmann said that it is unnecessary to run those passes because you cannot be reasonably certain about how a modern hard disk stores data on the platter. If the encoding is unknown, then writing random patterns is your best strategy.

In particular, Gutmann says that "in the time since this paper was published, some people have treated the 35-pass overwrite technique described in it more as a kind of voodoo incantation to banish evil spirits than the result of a technical analysis of drive encoding techniques. As a result, they advocate applying the voodoo to PRML and EPRML drives even though it will have no more effect than a simple scrubbing with random data... For any modern PRML/EPRML drive, a few passes of random scrubbing is the best you can do".

Read these papers by Peter Gutmann: