I believe there's no worse party in the entire ME region than Turkey.
They might be a NATO ally, but for years they have e.g. allowed free influx of foreign fighters and arms into the region and export of oil back into Turkey, thus directly fueling the rise of IS. (Granted, Saudi Arabia with sponsoring Wahhabite islam propaganda all over Europe also had its part)
Also, Erdogan is rapidly transforming Turkey to an Islamist dictatorship... and he's using the Syrian refugees as a weapon against Europe. Europe pays 3B € and Europe looks away from him turning into a dictator and massacring Kurds as long as he keeps the refugees in Turkey.
If Erdogan were to truly unleash the millions of refugees, Europe would be screwed. Europe couldn't manage the 2m refugees last year without nearly falling apart, another 2m (or more!) would break up the EU.