Which one should be prefered and why?

I prefer use base for three reasons:

• To me, it expresses my intent more clearly. I am using this module as a base class. When I have separate use/require and @ISA and have to expend that little bit more effort to associate the two.
• Less typing.
• Since use base does not die if the specified module cannot be required I don't have to change my code when I move between inlined packages and external modules