It really just depends on your budget. Obviously, PPC is instant but requires constant management in order to make sure that you don't go over your budget and once you do go over your budget the traffic stops just as quickly as it started.
As for SEO, it is extremely time consuming however, you can control or at least effect more organic results. You're going to have to invest what you can't invest financially, in time and be patient because the progress can be really slow. I prefer SEO because I don't see the point in creating a huge budget to compete with my competitors.