I own both the DX-1000 and Markl modded Denon D-5000. While both are superb phones, I much prefer the soundstage and imaging of the DX-1000. The JVCs have a more distant but larger and deeper soundstage while the Denons are more upfront, more like the Grado sound. The Denons, when compared side by side with the DX-1000s will strike you as brighter at first, but one soon becomes accustomed to the sound of each after a short time of listening.
The JVCs are physically larger and slightly heavier but both are comfortable when on the head. The JVC require a bit less drive than do the Denons.
You really should audition both in order to make a choice when considering cans of this quality (and cost!)