Everyone who is involved in online marketing has asked or is asking this question. The problem is basically money. If you have just started an online marketing site, you may not have the cash needed to invest in Pay Per Click (PPC) advertising. On the other hand, you have to spend time on Search Engine Optimization (SEO), so you might find yourself between a rock and a hard place. There's no doubt that both work, but with PPC you have an obvious advantage or two over SEO.

PPC is almost instantaneous and you don't have to redesign an existing site in order to place these ads. You can place ads on highly ranked sites in your niche and have a banner ad on Google's results pages. However, you have to pay per click whether or not the click results in a sale. If you have a PPC advertising campaign that is ongoing, then you will have to fork out cash for every click back to your site, regardless of whether the clicks result in sales. PPC advertising is far from cheap, but because search engine's get a lot of revenue from these ads, you get a better position on Search Engines Rankings Pages (SERPS) which is necessary for your site to be ultimately successful.

SEO on the other hand takes time, which means either you pay a professional SEO company to sort this out for you - which is also expensive, or you try and optimize your site yourself. Whether you are successful at doing this for yourself comes down to your creative, imaginative and writing abilities. You will also need to test the effectiveness of keywords in attracting traffic to your site and be prepared to change texts, titles and images so that you get the right formula. Once again all this takes time. You could use both PPC and SEO and test keywords success through your PPC ads. These can be quickly changed, and so you don't have to invest so much time in testing how successful they are.
PPC and SEO can go hand in hand, the choice is not an either or one unless you are on a tight budget of course. Then the question is should you invest in what could be a successful PPC campaign, or SEO? That is for you to decide, but consider this; the PPC ads may not result in many or any sales. SEO on the other hand will be an investment in the long-term future of your site. Good SEO services will suggest you use both I believe, but that comes at a price.

My personal choice would be for SEO rather than PPC simply because I can write well and have good content which attracts a loyal following, if you can't do this then you could hire someone who can - good content writers aren't that difficult to find and neither are good SEO services. I am also skeptical about PPC as the system can be abused and this is difficult to track immediately. However I see that PPC has many advantages in that as long as your ads are placed judiciously you get targeted traffic to your site and you will get more highly ranked in the SERPS.