Out of all of them, the X would have to be the one most people want. I want it. But $1579 is a lot of coin, and I have a 6S that works perfectly (and for various reasons it cost me nothing). I would be completely nuts to upgrade. There is no valid reason to do so. Not to mention the fact that although, yes, it would make me happy for a little while, once the dust settles and you've showed it off to a few friends and then I get back to my daily routine, it will make absolutely zero difference to my life whatsoever. In fact I could sell my 6S and use my Nexus 5X and also my life would barely change as a result, apart from my messages would be green on other peoples phones when they used to be blue.
Have a think about WHY you are upgrading. If it's just for a few moments of fleeting happiness, is that worth the $1579 you will be paying (and, presumably, the fun experience of trying to get rid of your old phone on ebay/gumtree/whatever)?