Here's what I chose.
#1 Matches and #2 knife. Because obviously.
Some islands get lots of rainfall and clean water, while others don't. Since I don't know which group this island falls under, I chose #3 water purifier.
After that, though, it gets more difficult. I can make cordage, so the rope is something I can reluctantly do without. The tent would be nice, the tarp maybe a little more versatile, and the inflatable boat offers both escape and shelter. The first aid kit looks like it will have lots of things useful not just for first aid. A mirror to signal for rescue would be nice, too.
I finally chose #4, tent. Because I'm just too damn old to paddle a boat across an ocean.
Onward and upward,
airforce