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 toSEO
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