SEO, is the first choice because from a strategic and tactical perspective. Using a more organic approach you can make sure that you have done everything possible for SEO Optimization before going the PPC route. Measuring either your activation or conversion call to action you can then tweak your approach and become smarter about what you are doing. Once you have done that should you choose to use PPC your ROI should be higher.

The real question is what is the right strategy for overall for the client. If immediate revenue is critical, and site traffic is low, PPC may be the way to go. In addition, the lessons learned from PPC will assist in SEO development.

Obviously the longer term value of SEO, with rated linking strategies will build value into the site.

I would choose SEO over PPC based on my previous personal experience with a multi-million dollar SEM campaign utilizing both methods.

The end result was that both methods drove traffic to the site and increased conversion rates, however, when the ROI was analyzed - the better investment was in SEO.

The PPC campaign was more expensive with less desirable results. It does need to be taken into consideration what market you are in and what you'll be paying per click as well as what position you are vying for. This particular campaign was in a highly competitive market.

I'm still in contact with the client and over a year later, the SEO campaign continues to drive traffic and conversion without additional funds spent.

I will be the odd man out and advocate for starting with PPC, particularly early on and for really competitive markets.

PPC allows you to investigate search engine user behavior, finding out what they search on, how often, and what language they respond to in ads and on landing pages. All of this is useful for downstream SEO efforts. PPC also has the benefit of generating business immediately, and if successful it quickly pays for itself, thus freeing up more cash for spending on SEO. As more websites become more sophisticated and good natural results are more difficult and expensive to obtain, PPC becomes more attractive. Consider also the relative risk of the two methods: PPC is relatively easy to control and measure. The return on SEO investment is very difficult to estimate because we don't know beforehand the likelihood for success, when it will occur, how much it will cost, and how long it will last without additional investment.

All of this being said, we look at each client individually, and almost all projects include elements of both PPC and SEO.

I'd choose PPC for the control. PPC offers the ability to change tactics quickly and measure the results more accurately. As the marketplace for our hosted telecom service grows and evolves, the need to change directions quickly to be able to seize new opportunities is very important. PPC would allow us the ability to make these adjustments with the least amount of time and effort and enjoy almost instant results.

At the risk of being labeled a flip-flopper I'd say it depends on the specific needs of the client.

If you want to get first page rankings and traffic immediately (especially for a new site) you'd better do PPC. For an existing site it might be worth the time and effort to do SEO. One factor is how much it would cost for your top keywords. Has anyone else noticed that bids just keep going up? Another good reason to opt for SEO.