I have used Adstream for my publishing/editing company and I loved how it was able to reach different types of clients in different areas of life. To me, that is crucial because I am able to reach a broader audience which in turn helps me package my product differently for different clients.
Tapjoy is awesome when you wish to advertise your app. User traffic can be achieved through campaigns. The engagement rate can be increased, which in turn increases business sales. The smart search option is very accurate and time-saving; I was able to search the term like ticket id. High revenue can be achieved.
I personally am not involved in the decision to renew the product, but I had only positive experiences with the product and thus would recommend its use and renewal.
I love Adstream because it does a great job at streamlining its ads to different components and different industry providers unlike Apple iAds and Google AdMob. It also is very helpful for a new business like myself to reach different audiences and hopefully generate some revenue from these types of diversified ads.
They have very different model of business, but I would use TapJoy as a complement of this other products. So you can expand the inventory where you buy ads and be able to scale more rapidly the growth of your mobile app.