I believe Princess Leia has the bigger tits between the two. Leia was incredibly hot in the first Star Wars (EpIV). I liked her as Jaba's sexslave in "Jedi" but she somehow wasn't as hot as she was in the first..
I would kind of be worried about them both. One is a women with borgish stuff still inside of her, and the other probably has some untapped Jedi powers at her disposal. They could both beat you up. You probably wouldn't even be able to hide anything from them ever. :1orglaugh
I didn't even know who Seven of Nine was, so I had to google it. Funnily enough, I used to jack off to her after school quite a bit but never even bothered to look her up.