Customs are quite good. I like my UERMs better than a great many headphones around their price or even significantly higher. The bonus for customs is that you can use them out in the world with their isolation (unless you get a vented model) and have high end sound wherever you go, even from just a DAP. I use my customs at home only, that should tell you I really prefer their sound over many standard headphones. The downside to customs is you really have to be sure which one you order since as you said you can't really resell it easily and even then for a great loss. Refit sounds bothersome, but isn't too bad in my experience. I had to get my customs refitted once and they were perfect after that. I wear mine about 10 hours a day and have zero comfort issues. Customs are generally high sensitivity low impedance so they respond very well to DAP-only solutions making a true portable solution. Customs also generally have better detail, soundstaging and bass due to the tiny amount of air they have to control in the canal and the location of the driver compared to full size headphones. The only headphones I would say have better of those are electrostatic headphones (certainly not portable by any means) and orthodynamic headphones like the Audeze or Hifiman planar types, but those are fully open and lack isolation.
Full size headphones are useful for more than 1 person, but the really good ones are open, so no go on a bus/train, etc. They won't stay in place well so portability is again limited. The sound can be better, but often it's the models that are highly resistive and require a chain of gear to sound their best, or even close to it. You see people with these gigantic bricks of 4-5 devices strapped together and apparently they call that portable... Closed models can sound ok, but their isolation isn't any better than a good custom or even a universal IEM.
As for the specific models you mentioned, the Ultrasone Edition 10 is one of the worst performing cans for the money I've ever heard. Quite bad. The JH3a/JH16pro is vastly superior, but I preferred the UERM. The big deal for me with the JH combo was the lackluster battery life ~6 hrs. This is probably enough for most people using it as a portable only setup on the way to/from work, maybe even for 2-3 days between charges.
For greater detail on these headphones see the link in my signature.
In summary, customs have a great deal more benefits than full size headphones when considering portability and using them from a DAP. Really the ONLY thing full size headphones have as an advantage is that they are not customized for you so you can resell if you chose poorly. Not a great point to hang your hat on, in my opinion. "Hey we might not sound the best, but when you figure that out, at least you can sell us easily"
many thanks for your advices. it turn out i have to choose the jh3a system with jh16 despite of the full size because i need to upgrade my computer. 