+1 for aptX HD
aptX HD is noticeably better than aptX. I'm currently previewing two ~$500 new smartphones, the LG G6 - International Edition (aptX HD and DAC) and the Samsung S8 (aptX), as potential upgrades to my LG V10. At first, Samsung's skin, additional features (iris scanner to unlock phone, edge swipe,), size, and drop-dead gorgeous design made me play with it for hours, while leaving the LG G6 to sit in the box.
Then, I decided to test their Bluetooth capabilities. From critically listening to several songs via Tidal on the PX's, I could tell that there is a noticeable difference between the two codecs. For songs from genres with less-produced music (jazz, classical) the extra information being sent through aptX HD improved several aspects of the music: separation, soundstage, fullness of bass instruments (bass, bari saxophone), decay of bass notes, and other details. The music sounded more dynamic and fuller on the LG G6 than the S8.
In terms of everything else besides SQ and durability, the S8 appeals to me more in pretty much every category, which makes me really think about where my priorities lie. On one hand we have what I consider to be the most cutting-edge phone line, hardware-wise, and on the other we have a very strong audio contender with DAC and the latest and greatest codecs. Oh well, that's a problem for a different thread.
PX's are great and they connected to each phone quickly without any troubles during comparisons.