Honestly the answers to these questions are highly relative and would depend on many factors and considerations. SEO and PPC both have their pros and cons. SEO strategy is used to rank your website higher in the organic search results of search engines. SEM (PPC) on the other hand involves paid advertising on the search engine results and other web pages.

Let us dig deeper into the subject by first busting a long held myth that PPC is costlier than SEO. No, it isn’t! In fact you may very well need to spend about $5,000 or more over 6 to 8 months, to get your page on top listing for highly competitive key words like weight loss or life insurance. A PPC advertisement however, can easily be seen in the visible spots on related pages. And it is relatively easier to control your budget for the PPC campaign.

A recent survey mentions that the websites receive 8 times more clicks from the organic search results than the clicks from PPC; however the goal achievement and conversion ratio is 1.5 times higher for the traffic coming from a PPC advertisement.

SEO obviously is a long term strategy. It may take about 3 to 6 months to see the actual measurable effects of the SEO campaigns. On the other hand PPC campaigns can give you immediate traffic. The biggest benefit of a PPC campaign is the speed of the expansive reach. It frees you of the headache of trying to figure out the search engine algorithms, and how can reach to the top position in the listing.
Thus if the website is about sale of products for Christmas where you would like to give away discounts and bonuses, the best way to go would be a PPC campaign. Because, in this case, it will be too late till the time SEO starts showing its outcome.
Another upside a PPC has over SEO is that the SEM campaign can be managed and changed in real time. PPC gives you the opportunity to hit the internet market with right advertisement at the right time thus grabbing quick eyeballs. With a PPC campaign it is easier to target large number of key words, whereas optimizing the website landing pages for a higher number of keywords is a highly daunting task. Hence a rightly managed and appropriately monitored PPC campaign will surly increase conversion ratio and gives a better ROI than a SEO.