1. Kat is missing an arm, and her head is shaved, only way she's hot is if someone has a fetish about robot arms.
2. Dare is not attractive, period haha.
3. Keyes, I don't like her hair style.
4. Dr. Hasley, too old.
5. Cortana, too holographic and blue....
Therefore, that makes the hottest girl in halo...Aunti Dot.
EDIT: 6. Serina, also too holographic and blue....