S9 looks awesome, a notable refinement over the S8. Stereo speakers and that camera! Let's not forget Samsung retaining the headphone jack either, a major win for those who prefer quality non wireless headphones. Having said that, I wonder if APTX-HD is supported by the S9 now.
I find headphones a very personal thing... Being an Audio Technica fanboy I have ANC9 for work (relatively fantastic audio quality/office sound cancelling, with Soundblaster E5), ADG1X for gaming + MSR7NC for music at home (on Soundblaster ZXR) - the latter being an indulgence so that I could have a pair of closed sets whilst working if noisy in the house, with a tiny amount of noise cancelling. Different qualities for different uses.
For the go I have the IM02s, but tips aren't the best so I'm currently using the AKGs that came with the S8+ (with Comply foam tips) - they work quite well.
I'm planning to buy an S8+ or similar soon, since its so much cheaper than Google Pixel, which isn't really officially sold here in Brazil (I loved my Nexus 5 though).
Mine's on Android 7.0. Samsung aren't too keen on pushing out updates in Australia in a rush; the telcos (Telstra) take their own sweet time too. That's where Apple has them soundly beat. Although, having said that, given last year's update history, perhaps Samsung's model is better after all - I rarely get breaking changes pushed down.
Plus they have dark mode for all their stock apps!
I will take Samsung, Huawei or LG interface changes over the defaults.