Agree with the Trisara/Amanpuri comments - Trisara hard product is excellent, although Amanpuri does have a classic appeal (103-105 are beautifully situated). Amanpuri wins on service, beach, and I also love their gym.
Iniala is great in its own way. I wouldn't call it a "resort" in the same way as the other two; it's basically 4 villas, a beach and a gym (and a restaurant which may or may not be open depending when you visit). But if you really want to hunker down and see no one other than people paid to take care of you, it works well; and they do bend over backwards to cater to your every whim, from your 2 butlers, to the amazing instructor in the gym, to the chef. The kids hotel was also great for us but I'm imagining you're not honeymooning with offspring in tow. Design-wise it is definitely novel in comparison to the other options. MacMyDay wrote an extensive review (which helped plant the seed for our visit a couple weeks ago) and I agree with him that the Penthouse is the best option here. His review should help you figure out if this is the right place for you.
Between the three though, if I were forced to pick a phuket honeymoon destination right now, I'd probably still do Amanpuri...