List your state of art headphones for smart phone use!

Do headphones get any better than the Koss Porta Pros? 

Not heard Stax, not heard HD600s but out of all the ones I have heard up to 4/5 times the price none of them have spanked the Pros when it comes to sheer joy and life in the music. In fact some of them have been real dullsville efforts.

I'd love to hear some Grado woodies (if only half the stories are true!) but they wouldn't do for portable use.  

Mr Speakers Aeon Flow closed

Pros: Very low leakage. Decently isolating. Have low enough impedance to be driven to decent levels by the amp in a phone. Sound world class when paired with a headphone amp with some guts. Wire based headphone band very innovative and takes torquing/twisting with ease.

Cons: Don’t fold down nicely to fit anywhere. Ear pads are fragile enough to maybe not want to travel with.

I agree with mijostyn re: the Etymotic Research ER-4. They are very small, light, portable, relatively inexpensive, durable, noise-isolating, and (most importantly from the audiophile perspective) they sound quite good. I use them with an Audioquest JitterBug and the DragonFly Red when I'm on extended airplane flights (fortunately, not that often) and when I'm sitting outside reading or staring into space. Better yet, they actually stay in place and sound good when exercising (e.g., a half or full marathon). Only problem: microphonics (noise from the cords) unless you're stationary.
Keith

Not sure if state of the art but have given me literally 100,s of thousands of miles of service.
In fact when I watch my fellow travelers all unpacking their  bulky over ear phones and looking for charging ports I can’t help but chuckle.
I drag out my pocket this tiny black pouch with my own phones inside and plug and play.

Klipsch R6, still using my original from 6 years ago and I am a Delta Million Miler and I hammer the heck out of them.
I did buy a pair of the R6 mk2 but not even opened them yet.
All phones I have used them with have more than enough grunt to satisfy me, makes watching an in-flight movie more tolerable too.
Ultimate bass maybe a bit shy but mids and treble are superb.
Oh and 6 hour flight comfortable guaranteed!

On ear but:

https://www.amazon.com/gp/product/B008AT6DMC/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1