I'm only speaking for myself so I don't know if others feel this way but for me personally; the reason I liked Ashlotte is because even though her design was a bit over the top, it still looked more interesting then the others in my opinion. I liked the Steampunk theme the creator designed her in and plus, her voice wasn't all that bad compared to the others. And I remember when I first played against her in story mode and she does her little intro where she spins her weapon, then falls on her bottom and stands up saying "What are you afraid of?", I was like creeped out yet intrigued at the same time. So that's my reason why I liked Ashlotte more then the rest.
I didn't like Shura because her design looked awful. Very desperate looking in my opinion. And her slutty demeanor annoyed me a lot. Kam because while I did like the Oni concept, I didn't like how they executed it with a very anime-like character and her overall design didn't appeal to me really. Angol Fear because her design was beyond awful and her voice was gah... And lastly Schewerhazade (I probably spelled her name wrong) because I hated her design and her voice had to be the most annoying out of the bonus characters. But all this mostly because I'm not into overly anime designs. But remember, I'm just speaking for myself. I'm sure they had/have their fair share of fans. :)