Ooooh Eeeer, which 4 to choose.
1. The classic design Ray Mears bushcraft knife.
2. A decent length of 5mm or 6mm kernmantel...........550 is ok, till you start trying to use it with a fire-bow then it is as useful as a chocolate ashtray. 5mm/6mm kernmatel is excellent for fire-bows and is also generally as useable as 550 for camp tasks. I used to get my guys to swap out the draw cords in their jackets for 5mm kernmantel.
Everything after those two items is a luxury.
3. My Ti mug.
4. Coffee.