title_body: What coffee and roast are best for Turkish?
upvoted_answer: I believe the answer will be subjective. But, I can answer based on some tradition and history.
  
  The coffee beans were originated from Yemen in Ottoman Empire. At least, Yemen was a hub. (This fact is even mentioned in folk songs. See here and here.) Historically, Robusta beans were not around, yet. Americas were not explored. So, if you want to follow the tradition, stick with African originated Arabica beans. Still, one should note that if you go for the current Turkish commercial ground coffee brands (like Mehmet Efendi, etc.) on the market, most of them include mostly Robusta beans from South America to keep the costs low. This is ugly face of horeca, I assume.
  
  (African originated Arabicas are also my personal preference. My favorite is Ethiopian Harar. As far as I experienced, it is even better than Kopi Luwak for Turkish coffee. Also, this may be a hint. Kopi Luwak is known for low acidity. So, low acidity beans were not good for my taste even it was Kopi Luwak. On the other hand, Kopi Luwak was great while brewed with pressure.)
  
  For roasting the beans, you generally do not need to burn the beans to eliminate the acidity. So, light roasts are OK for Turkish coffee. Majority of commercial brands prepare City roast and the minority prepare American roast (I think). If you taste burnt flavor in a package, it is clearly over roasted; you must be suspicious about the quality of the beans.
  
  (My personal preference is a bit darker than that. City roast to full city roast.)
  
  Last words: I think, as Turkish coffee is just a brewing method, it is up to the drinkers taste either to add sugar/gum/cinnamon/milk or not, either to use Robusta or Arabica, either to roast light or dark. I mean, if the drinkers find it more delicious, they can boil it up for hours (It exists!) before drinking. This is about the taste, so no boundaries. :)