Good language skills in Greece
I don't know what bad experiences Stratobus had, and I am not competent to argue airline matters with a scheduled pilot, but as a PPL holder with just over 200 hours (most flown in Athens TMA area in Cessnas or Pipers) I can definitely state that Athens Information (130.925 or Athens TMA 124.025) have absolutely first class English. I have never had any problem with them - neither in understanding the instructions, nor in their pronunciation and command of English (unlike Tatoi Airfield, where English skills are often at a much lower standard and which is Military).
However I would also like to commend Megara (which is also GA and Military) on the consistent high level of their ATC.
Generally speaking, apart from Athens I have found good English language skills and professionalism at Corfu, Thessaloniki and Skiathos but I have occasionally had poor ATC at Heraklion.