Dear Friends, regarding South Korea you have to keep in mind that the lectures are some time in Korean also(Hanyang University) because one of my friend is doing MS leading to PhD from there, and he told me we are now learning Korean.
(Regardless of the fact they say courses in English, but actually they speak Korean most of the time)
Regarding METU, I heard from one HEC Scholar that there is 100% english. All the courses are in english, and i.e why they require IELTS 6.5(Mandatory).

Before taking decision please confirm it from your seniors there.