For me it's the HTC 8X. I originally bought a Lumia 920 based on great reviews, but after a week I hated it and took it back and exchanged it for the 8X which I love more and more every day. The main reason is the Lumia 920 is UNWEILDY. It is heavy, too wide for comfort, slippery, and has straight sides, making it very difficult to pick up confidently with one hand without feeling at risk of dropping it. Picking up my phone is something I do dozens of times a day. The 8X in total contrast is light (yet strong), narrower, has a nice grippy surface and is bevelled at the edges, so that with one hand I can easily flip it up into my palm with great confidence. It just feels right in my hand and I can hold it for long periods without my hand getting tired, which was not the case with the 920: no matter how much I tried to convince myself I would get used to it, I just didn't. With the 920, because it is heavy and slippery I had to hold it more firmly. This resulted in me repeatedly activating the camera button accidentally, because the button is actually quite mushy and placed right where you grip the phone. I was expecting big things from the 920's camera. It does very well in low light, but overall all images where very soft focus in appearance, too soft to the point where they all seemed out of focus, and just didn't seem right. The 8X's camera to me gives nice sharp photos, so I'm happier with that. I also noted the GPS in the 920 was very laggy and I couldn't navigate effectively from it. It would generally be about 30 seconds behind my actual position when driving, so that I would be 2 or 3 blocks past my turn-off before it updated the screen. My 8X updates the screen every 2-3 seconds, and also has downloadable maps now, so that you can navigate outside 3G reception range (I wasn't actually aware of this until after I had purchased the phone - a nice surprise because I had decided to sacrifice that feature of the 920 to get the more ergonomic 8X). Sure, the 8X only has half the memory of the 920, but I don't store masses of music or video on my phone so it's irrelevant to me.
I guess much of this is personal preference. My personal take is that the Lumia 920 is beautiful to behold, whereas the HTC 8X is beautiful to use (as well as being a stunning, ergonomic design in my opinion). I wonder how many reviews are based on the initial "wow this looks good" effect, and hence why the Lumia 920 has had such good press. All I can say that having used both of these phones for good periods of time, the 8X is easy to love, the 920 just frustrated me.
There, that should stir up some comment...