My two cents...
I heard a lot of stories about Turkish ATC because I worked with ATCOs that had been trained in Turkey. They have very positive attitude towards people and organization . Having no own experience I will leave to others more details.
About Turkish airliners...
I will agree with above posts ,more or less they are correct.
I will just add my personal experience.
THY- For me the same level as DLH and BAW,no difference. Excellent job


Quite reliable.So far I haven't have any problem.
ATLAS JET,BLACK SEA(know also as MNG) and other Turkish charters,
WARNING ,
I always taking some level of precautions .years of experience with those airlines bring some new rules for me.
DOUBLE SEPARATION i.e. instead of 5 Nm or 1000 ft, I applied
10 Nmand 2000 ft. Sometimes even such type of separation may be inadequate.
You may expect everything from crews.
One thing is as a rule when they are involved.
It is not question will they make mistake or not.
It is just question what will happen.
having that in mind I always regret over the Turkish ATCOs destiny.
They work with them more occasionally.
Just to quote local representative of Turkish airlines.
MNG ,NO GOOD!