I've tried quite a few different straps on my UX, including; Sinn rubber, leather, Hirsch, Isofrane and several NATO's. Up until today, my favourite was the Isofrane.
The thing is though, I've always liked the concept and looks of the NATO strap, but found the increased height at odds with the bulk that is the UX. Plus, those I've tried always seemed to be too loose or too tight.
Today I rediscovered the two piece NATO (OK, a two piece Nylon strap that resembles a cut in half Zulu) that originally came with a G-Shock. Given that I was messing around with other straps at the time I thought "why not?"
Result? Well its a RESULT! Comfortable, holds the mighty UX rock solid and low to the wrist, and all the hardware is centred nicely under my wrist.