Yuka's are nice. I'm sure there are more, but I'm having trouble thinking of skaters who hold their spirals long enough and/or a have Button-approved foot position on their laybacks.
For layback, it has to be Angela. I think Dick would return from the refrigerator break just long enough to mention that her layback is the best in the business (frivilous frumpery aside).
Maybe kwan could represent China and Cohen could represent Ukraine (and Nikodinov could represent Bulgaria) someday. That would make more room for other US skaters... (j/k)
For layback, Ruh's incredible. She's practically a contortionist on her spins.
As for spirals, I don't think anyone can come close to the American ladies for extension and maintaining the position. Irina's does have an edge, but she seldom holds the extended leg in a nice position for the entire movement. It's hard to judge because TV doesn't focus only on the edge and it's easier to watch the extension.