I generally prefer to use parens, but be aware that the following two statements are not identical:
in reply to A question of style
If you call a sub with empty parentheses, the called sub has an empty @_. However, if you call it with a preceding ampersand as in the first example, the current value of @_ gets passed to the sub that you call. This is most useful when calling subs from subs.
This is more than just a matter of style. If you're not aware of that difference, coming back later to maintain that code may just break it. As a result, I prefer not to use ampersands when calling a sub unless I specifically desire to pass the contents of @_ to the called sub.