1. Great support
2. 'Audiences' for black-listing and white-listing. This means you can have a single list of zones (sources) for multiple campaigns. Changes made in the list instantly appear across other campaigns, since it's actually a single list, shared between them.
3. Automated rules
Let's say you set an auto-rule on one campaign: if the zone (source) has 100 clicks and 0 conversions - put it into the blacklist. So you exclude automatically red zones. Plus, if the list ('Audience') is used as a blacklist in multiple campaigns, the zones will be excluded in all of them. The same goes for whitelisting.
4. Smoother traffic distribution between zones. Once you start a campaign, you can see in a tracker, that a big bunch of zones get a similar amount of clicks. Not like some other networks, where 5 zones eat up all the money until you exclude them.
5. Changes in CPC or start/stop take effect VERY fast. You can change CPC and in 10 minutes the tracker shows the changes. The campaign starts very fast.
6. They don't 'hide' traffic from you, as others do. If you have a few profitable zones, you can get traffic from it as long as it burns out. But you will actually GET the traffic. For example, on PropellerAds, they will say your targeting is too narrow and you'll get a drop in impressions. On EvaDav you get what you expected. If the zone gave you 100 clicks yesterday, in the whitelist it will continue to give the same amount of clicks!