and I admit that its strongly as a result of my personal Real Life belief system. I'm going to go with the fact that neither one of them have physical bodies as we know them. Neither do they have gender...as any gender associations are for human understanding. But seeing as how this doesn't always work out, if they had physical bodies, I seem them as this.

The Creator...the classic old man look.
The Dark One...the good looking young man.

In the Bible, Lucifer was described as a very attractive angel. There is the commonly held belief that he was also in charge of music in heaven. I can see this type of thing very much as a look at the Dark One. Only who he is on the inside is that shadow like figure. Its his touch, his throughs, and his actions which are dark and "light-eating". I find this far more apt. Look at the Forsaken. At their most ugly, they were handsome or at least pretty looking (not counting Aginor & Balthamel since they were affected by the passage of time). Several of the Forsaken are regarded as very good looking (Lanfear, Demandred, Graendal). It would also fit with the persona of being completely selfish and narcasistic.

~Jeordam