I actually don't like Ksenia Triss cosplay, though she is indeed a gorgeous woman. I absolutely adore feline like eyes and face shape. Not like Jessica Nigri or Megan Fox, to name a few, that are still beautiful but too vampy or too "trivial" for me. I think I would go mad to see Nigri portraiting Triss.
Mixed feeling about Klodi Monsoon, really.
Anyway I still think that Selen-cosvamp is a fine TW1 Triss
And could perfectly compete with Miss Ksenia.
Anyway, if Triss would be real, since it's a character of a Polish author, it would certainly be a Eastern Europe beauty, like
@slimgrin said above. I don't think that any Umpton or Fox or -insertaHollywoodbeauty- would fit.