|The stupid question is the question not asked|
I wouldn't necessarily say "the best" documention, but both Pod::Usage and Getopt::Long have documentation that are spiritually akin to Perl itself - easy to get started with, yet no dearth of depth. So much so, that even a lunkhead like me easily figured out how to use them* with a degree of effectiveness.
striving toward Perl Adept
(it's pronounced "why-bick")
* shameless plug
In reply to Re: Looking for Mr. Good Documentation! (apropriately enough...)