Emirates is likely to be #1, primarily due to the size of their order. But the whole 'launch customer' thing is a bit confusing, LH has also claimed to be launch customer by dint of being first airline to place an order (way back in 2013, can you believe it!), while 'launch customer' status has also been cited by QR (most notably by former CEO Akbar Al Baker). I'd put my money on the batting order being EK, LH, QR.