The three items I would grab (or more likely get stuck with) would be;
A Multitool- because it'll give me the illusion of productivity
A book- I have absolutely no focus or drive so i'd probably end up reading a book for a bit
And thirdly, I'd go for A blanket- nice to cozy up with, because I have no doubts I'd barely survive on an island but I know i wouldn't be able to get a fire going on the first night there