It is plain to see that each tool is good depending on those tasks which are set prior to the launch of advertisement. In case of urgent need of sales, and you wish to attract as larger target audience as possible, then we should switch on Yandex Direct or Google Adwords. If we intend to enhance the general awareness of the brand or of any specific goods, then Yandex Advertising Network should be your choice. Let us also note that we do not like Google Display Network as far as the websites where they place advertisement are much worse in terms of quality than in Yandex Advertising Network. These are the consequences of those times when Google paid large sums of commission fees for switching from the partner websites, and a vast number of site webmasters jumped at hammering websites for those affiliate programs. After a while they tightened the screws, reduced payments but these websites remained in Google Display Network.
Each tool may both generate value and inflict damage. The most important thing is to know when and in which cases these tools shall be used.