I voted to polish but it really depends. I don't mind a smooth satin finish on the component in most instances. If the bike was well cared for a kept inside then I probably would do anything more than clean everything and maybe rub it with some simichrome. But if the part is heavily oxidized and looks bad then I polish it. Depends on the part too - I always polish rims, stems and the exposed section of the handlebars. I rarely ever polish brakes, cranks, derailleurs and such. And of course there are exceptions. The Stronglight 49D crank on my Bottecchia for example came with a highly polished finish rather than the satin finish like Campy stuff so that gets polished.