for the behavior, besides all of the above posts, also consider this simple example:

  my @x = ('a' .. 'e');
  my $y = @x;
  my ($z) = @x;
  warn $y;  # 5
  warn $z;  # 'a'
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Because, in scalar context, an array variable will evaluate to it's length.

I'd say that, in general, it's "more appropriate" to declare in list context only when list context is actually needed -- e.g. declaring multiple variables at once, or sometihng like the my ($z) = @x; above where you're working w/ an array on the RHS.

Another common use of list context:

function foo {
  my ($bar, $stuff, $blah) = @_;   # get the arguments
  ...
}
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