Whether the flight is worth it depends on what you value in a flight, I'd say! If you are collecting M&Ms, TK should earn you at least 50% in Y, provided you're in the right fare bucket.
If you have no status and are flying in Y, your choice of airline won't make a huge difference in this case. IST can get quite crowded at times so you may be able to choose an alternative transfer airport that would be less busy. For 21 May, I found an AF fare that connects to a very fast train at CDG, for example, which ought to make a less painful transfer - but as I said, it really depends on what you're looking for in the experience!