As far as features go, the Das has the benefit of a USB hub and a longer cable (although the WASD comes with an extension IIRC). I'm not a big fan of the former (too much convenience makes you lazy

) but the latter is great because I occasionally unplugged my old keyboard by accident. I got a Das Keyboard Ultimate, so even though the Professional's keys are lasered, I won't have to deal with fading keys at all. Plus, blank keys probably are easier to customise should you decide to do so.
Alternatively, if fading keys are a big issue, you could get a WASD with engraved key caps. Or you could buy an engraved cap set from WASD and put it on one of the others if you like their design better. Although that would be more expensive and I have no idea how well they fit on a Rosewill or Leopold; the Das has similiar or even the same key caps as WASD from what I've read in another thread.