Nadia was my favourite, she was my main motive for leveling and with getting her so late on in the game, I cleared a lot of content very eagerly to get my very own padawan.
I'm not going to lie... hearing "Yes Master" to my commands makes me feel like a boss. And I agree, the "It.. Hurts" did sound a bit erotic, but I have a dirty mind . It made me LOL at first but playing as a healer, she hardly said it at all.
The great thing about her is she can use all my old gear, she is currently fitted with a lot of champion PvP gear and she rocks! So not only is she my favourite companion for her story/relationship but also because gearing her up is very easy.
She is going to have a big fanbase with the male gaming population I think. She is everything a man wants.. obediant, loyal, cute, protective and has a kind/loving personality. She is a bit broken and vulnerable by her fathers death and we step in off the rebound to make her feel better lol.
That's my 2 pence anyway.