They're two pretty different watches really. If it's the D-Blue you mean, it's probably not as good an all-rounder as the standard black dial, but I really like it myself and see the attraction. It's a very tough watch though the Deep Sea and wears better than most people expect, as it's quite flat against the wrist.
The YM is also very nice, with probably the most unique case profile in the Rolex line-up. However unlike the ceramic bezel of the deep sea, the YM bezel has a polished and bead-blasted finish which, if damaged or scratched is not an easy fix. Worse still, it's obviously platinum and should replacement be the only option, you're looking at well over £1000. It's a wonderful watch but this put me off them when I found this out.
You must try them both and see which fits you best in terms of wearability and design I reckon.