Ether between Alexa Bliss or Sasha Banks. Alexa because of her bitchy heel character and how she has yet to really get her comeuppance because of how she's been booked since being drafted to Raw. A good foot tickling should be significant. Becky, because of her "tough girl" persona. Those girls are sometimes the most fun to tickle.
Special nomination or Paige. Wouldn't might tickling her, especially since it's been exposed that she is very ticklish. And I don't really want to tickle Nia Jax, but a what if scenario with her being the most ticklish woman on the roster and being destroyed by the other women on the roster with tickles is just a hilarious visualization for me.