in reply to
die or croak
If you get an exception because you misused the API of a module, you usually want to know where in your the error is, so you're happier when the module called croak().
Of course that concept breaks down when you write a module that uses another module which uses croak() -- the errors will come from your module, not from your module user's code.
In the case of internal errors, modules should use die, or maybe even Carp::confess.
(Oh, and if (as a user) you want to get a backtrace no matter what, use Carp::Always).