An inflatable raft is a really bad way to get off a deserted island unless you know where you are, where you want to go, and the wind and water are very cooperative in getting you there. The island is almost certainly a better place to be than on the raft.

For me, it's water purifier, knife, matches, and tent, in that order.

Without water, I've got three days to live. With a knife, I can make shelter and have a good shot at making a fire. With the tent, shelter gets a lot easier, and ditto fire with the matches.

I don't need a mirror if I can build signal fires. An argument could be made that the flare gun could be used for signalling and for firestarting, but I think I'd rather have the matches.