Nexus 5 or Note 3, but given the chance now I would still probably get the HTC One again.
Design is holding up really well, love the speakers and audio quality, use the infrared remote all the time, the camera still is pretty good even in daylight and still one of the best in low-light versus some of the newer phones, slow motion video, no lag even after several months of use, development has been quite competitive with some of the other flagship phones (I have dual-boot GPe and Sense 5), highest DPI screen of any smartphone (and one of the best overall), 32GB onboard storage is standard versus 16GB for some of the other phones, and the Media Link HD is the only Miracast streamer that works really well (that I know of). Awesome being able to both use my phone to stream content and mirror my phone to my television AND control my receiver, television, FiOS box, etc with ease.
Only downsides thus far: takes longer to charger than most phones, battery life is fairly average (lasts about as long as the S4's standard battery, but less than the G2, Moto X, DROIDs, and Nexus 5).
Otherwise the non-Android phones I'm interested in are the Lumia 1020 and 1520. Probably wouldn't buy any other phone over the One. Next year there might be some models that interest me, though.