It's best when dealing with several clients, products, and creative materials. When dealing with a high volume of creative materials to be trafficked to several different networks, I'd recommend Adstream.
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.