TK hands down.
LX J is a very dense cabin, even for couples. The deal breaker here for me would be ORD. Arrival in T5, going thru customs, and then trekking to the terminal where AC departs from, also waiting 5 hours after a long flight at a United Club. All dreadful.

TK, when you reach, you ll be at your destination, and you still get to use the Swiss lounge in ZRH, and then the TK lounge in IST. And you avoid the US (and save $50 in tax).
And you dont have to fly AC at all, which in itself is a huge plus.