Ismat isn't physically cute, but her personality is endearing; Candas is physically cute/sexy with a generic personality.
Ismat. Personality has always mattered more than appearance.
I have a thing for brown skin (and pet tigers), so Sabera gets a point there. However, her personality isn't defined; her story is guided by everyone except her.* Abby's not brown, but her personality is defined well and I find her very endearing.
Abby has my vote.
Vanya has a goal and a purpose, but nothing immediately endearing.** Ariane's bio is nice and short, but it doesn't say much either. It sounds I'm being introduced to a friend's friend, and said introduction matters much less than actually meeting the person in question.***
I vote Vanya.
* It's difficult at best to make a primarily passive character (e.g. Bella Swan) likable. "Woe is me, curse my curse" makes it even worse, because time spent complaining could be spent fixing the problem.
** Flaws are the easiest way to make a character endearing (not the only way, mind you). They make the character seem human and approachable rather than some flawless demigod or emotionless badass (compare pre-2013 Lara Croft to the current Lara Croft).
*** This is why Valve advertises Team Fortress 2 with "meet the [character]" rather than "be passively introduced to [character]." Watch those sometime. Valve is excellent at developing likable characters in a very short time.