Depends on what you're in the mood for...? I've seen Ashley and Kimberly many times each, Jessica only once. I would see Kimberly if I wanted a good switch, but she goes covered both ways which is a let down. She's sweet and very reliable. She is a very sensual top, she can lay down a great fuck.  
Ashley is more of a bottom, but claims to be verse, although I haven't been topped by her. She does get very hard so I could see it. She is ok with bbbj both ways. She is fun but flaky and can be difficult to reach.  
I think Jessica has potential to be a good switch or even a straight top. She said she prefers topping, and her extremely functional penis backed up her claim.  
I've never seen Kimberly cum, but both Ashley and Jessica have cum.  
So, I guess my answer is...ALL THREE! Hahahahahaha!