I was in Hong Kong when the first G-Shock came out. It was then quite a revolution in affordable durability and I believe it still holds a few records. After almost 40 years and 200+ different models, it comes with all sorts of useful built-in features. I was collecting gadget watches at the time but I skipped the G-Shock, opting instead for the Citizen ProMaster Tough with its solar cell, titanium body and kevlar wristband. I somehow misplaced my first copy in the 90s but was able to buy a new one last year; it comes and goes from the catalog.
There is a new version of the Breitling Emergency with a 406MHZ transmitter that can reach satellites directly but it is huge, needs to be recharged regularly and costs $15,000. The good thing about the old 121.5MHz version is that you can wear and forget it and it will be there if you need it. Airliners still monitor 121.5MHz so your signal is likely to be picked up in most of the World. A satphone or pocket ELT work fine (I use both) but you are not likely to wear them 24/7. As the classic Emergency watches are no longer made, I am tempted to get another one, second hand, as a backup. That said, the one that is my everyday wear is now 20 years old, has been banged up all around the World, and is still doing well although it does get sent to Switzerland every two years for a month long service. Its only weakness, as far as I am concerned, is that you cannot scuba dive with it. There was a stainless steel version (the “Mission”) with the proper depth rating but much too heavy to be comfortable. Having said all that, If I was looking for a TEOTWAWKI watch, I’d get something completely infallible that would just tell the time for ever, like a Rolex submariner.
I am surprised the aforementioned Rolexes didn’t make the list: they are bombproof and will work for decades without a service. They are, of course, very expensive. Putting durability first and going on a budget, two more obvious choices are the Seiko 5 SNK series (stainless steel, automatic, starting under $80) and the Citizen Promaster Tough (titanium, solar, $360). At the other end of the scale in the “tool watch” category, I’d go for a Breitling Emergency (titanium, quartz, only second hand for under $4,000 with the 121.5 MHz built-in emergency transmitter) if emergency services are still running, or the Porsche Design P’3511 (titanium, mechanical, built-in removable compass, one of the most cleverly designed watches in history, second hand for around $5,000) if you can only count on yourself to get out of trouble.