My 11-year-old daughter asked me this today: If you had to choose just one item to carry on you for a real-world lost or stranded-type situation, what would it be? How about two, or three? The question made me re-think some of my previous ideas. I've been looking at the things I carry from the perspective that I have a backup for this or that, so it need not be bulletproof.

Here's my partial list, ordered by priority:

1 - Knife
2 - Lighter
3 - Paracord
4 - Flashlight
5 - Compass

This opened up a whole new can of worms for me, since my EDC knife is a cheapo "Smith & Wesson Homeland Security" model, my EDC lighter is a Bic (not too bad as far as quality goes), and I don't regularly EDC a flashlight, compass, or paracord.

I'm looking online right now for a bombproof folding knife, good flashlight (Photon maybe), and a beefy but small compass.

#3, Billy can.
Oop's I re-read the question.
For one item only then a blade wins.
If I was adding something to your list it would be a Billy can.
If you are looking for a decent small compass check out
a Silva watchband compass. They are sold with a velcro watch strap and have a ratchet bezel. I have never had any issues with them, they are dependable.

What I found out about bic lighters is the button can get compressed and empty them. I try to get the ones that lock the fuel off when I can. I couldn't find any friday so I bought a package of bics again.

I have several good compasses but I always have one of the little button compasses like Doug sells, and I have one of the Brunton compasses (with a thermometer) as a zipper pull on my jacket.
They are not good enough for survey work, but they are small enough for EDC and do give me magnetic north within a few degrees.

A bomb proof folder?
I have an auminum SAK Soldier that manages to be EDC.
It is not too big or scary. I wish it was an easy open lock blade.
I often have the Spyderco Endura in another pocket though.
It is a bit large and a bit scary for people, but it has lasted a very long time with no problems.
Doug has a pretty good folding knife for sale too.

I almost always have some string around. It is not quite EDC with me though, unless you count shoelaces and so on.

If I had to chose one and only one item it would likely be a lighter.
(Errr, no, a knife, a lighter, a compass, a knife, a lighter, some line,....)

This is the classic problem with trying to figure out the minimum kit. It is real easy to find yourself hauling all of your camping gear everywhere with you, and even if every piece of gear is super small you can still load up tons of trinkets.

If I had to choose only one item, it would be a knife. After that, I would want a lighter and something for water containment/purification.

A knife. Worst came to worst, you could use it to obtain the rest. Um, if it was a big knife. Which presents its own problems.

1. PLB - that was an easy choice

2. This is actually a tough choice for me.

If I have the PLB, my primary objective is to be as "findable" as possible, so by day I would want a signal mirror, and by night I would want a bright light or a fire. I think I have a better chance of being seen by day without a signal mirror, but by night ... I'd say #2 Bright Flashlight. Under this scenario I'd say #3 is a bright (orange?) shelter material, as this would help me get found by day AND be a shelter against the wet & cold of night.

If I did not have the PLB, I feel like I should say the next item would be a knife, but the truth is that fire is so important for warmth, mental health, and signal that I think I'd have to say #1 Good Lighter or sparker & tinder, and then #2 Knife. #3 would be that bright shelter material I mentioned above.

I wish I could find a high quality bright orange poncho.

The rest of my necessity list would include a whistle, signal mirror, cordage

What I was thinking was maybe a Photon and a zipper-pull compass on my keyring. I'd like both to be tough as nails. If no-one makes a really good zipper-pull compass, I'll epoxy a really good button compass onto a piece of Lexan myself.

My thinking on the knife versus lighter issue was that I can start a fire with a knife (bow method or fire plow) but I'd have a hard time cutting something with a lighter.

1. edc gerber folder.
2. lighter
3. Poncho
4. whistle

i do not leave my bedroom w/o my pocketknife. i have learned that where i live if i don't have it i will need it. poncho was almost a tie with a firestarter poncho= shelter, dry, signal, groundcover, water gatherer/carryer, it is basically a must have. and i can yell loudly, but for how long? whistles can be heard for a couple miles, and don't go hoarse.

Poncho or similar - in a real wilderness situation getting shelter is issue one, and you'd be best to assume it's wet, dark and you are injured. Getting out of wind/rain until dawn or rescue is priority one in a lot of cases, so something I can wrap myself in or crawl into would be best (even the hated space blanket would be better than nothing)

That said I consider a small knife, lighter and torch to be the edc trinity. And frediver has the correct on a cook pot - valuable and hard to improvise