I don't use either one of the above.

For a simple command with no args to the sub, I often use:
-command => \&some_sub_name

For a command with args to a sub, I often use:
-command => sub { some_sub_name ($arg1, $arg2) }

The previous is an anon sub that calls some_sub_name(...)

There is no need for the '&' below and I would recommend against it.
-command=>sub { &some_sub_name($arg1,$arg2) }