Hey....
SEO
1 No worry on click frauds
2 Large number of visitors ->economy of scale
3 Search Engines Algo keep changing affecting SEO.
4 Takes time to get top ranking
PPC
1 Immediate result, fast ranking
2 Long tail keywords are more economical compare to SEO
3 Cost will be relative high if people keep bidding for certain keywords
4 Click fraud always a problem
PPC is more suitable for long tail keywords while SEO is more suitable for more generic keywords.

but getting traffic using SEO is some bit difficult ,
and there is a big competition going inside ,,,
and i dont care about PTC sites, they are not reliable traffic , and we con't convert those traffic into revenue ,
but CPC is some bit good

PPC advertising is mostly done and use when the keyword is long and also it is like pay per click and the seo is done when the key word is small and the generic . also the seo is more famous and trustful then the ppc.