Out of your list, I would say Aspen. She has some of the best abs genetics I've seen in terms of shape and the fact that they're almost always visible even at higher body fat. When she get's really lean and flexes, they're truly unreal.
I might, personally, add Rachel Scheer and/or Martina Sletsjoee to that list as well.
Maybe not the absolute best, but a very pretty woman with great abs and veins, Karen Zaremba.
As you might be able to to tell from my username, I love abs. I've compiled a list of girls that I think have fantastic abs. The only problem is, I can't choose who has the absolute best. Who dou you think has the best out of the girls I've listed?
Stefanie Macherhammer Aftan Noon Senada Greca Zuzka Light Vanessa Serros Abbi Kianpour Aspen Rae