I need an idea for NaNoWriMo. I have a few of them, which do you like better?

1. A girl gets cancer and it goes through the ups and downs of her getting sick and better, then getting sick again.

2. A group of people are on a plane when it crashes and they get stranded on a island for 3 months. They make enemies, friendships and fall in love.

3. A group of teenagers stay in an Amusement park after dark and then strange things start to happen; the rides go on their own and the workers seem to be dead…

4. A story about a teenage girl who falls in love and then gets pregnant (in young teens 13-16 unsure yet). She goes through her parents wanting her to abort and her wanting to keep the baby.

Which is the best idea and why?

Plz and Thanx
- Bella Cullen