Although you'll have to wait til 2018 if it does actually get released. Seems a bit crazy though, 3 CPUs, 18GB of RAM, 768GB storage, and a hydrogen fuel cell-equipped battery.
My favourite is Smart Keyboard Pro. I tried a lot out when I got my last Android phone, and despite the high feedback, I never liked SwiftKey due to the developer's insistence with certain features that "We're right and you're wrong". Hence no way to turn off that annoying click and swipe for certain punctuation marks, and there was another dumb default option that annoyed me too that couldn't be changed (can't remember what it was now).