With the pay per click option, publishers are sure to earn an income. This option, however, is ideal for those who have the budget because a PPC campaign is normally paid unlike the other free options. But a little investment on this won’t hurt as one can possibly gain a good return later.

PPC works but some point play very important role.
1. deside budget carefully
2. deside per click amount care fully
3. make a good ad for display   

To me, content PPC is only as effective (sometimes more effective), when you are linked to some killer content, or to sites with decent content but have a loyal following or a popular contributor. Search PPC is just more consistent in my opinion, and therefore a better marketing tool. Having both will do better for you in the long run. I'm not fully familiar with content PPC campaigns these days, but I believe they would build your search ranking - someone please correct me if I'm wrong.