Watches

For actual going up in space, Hesalite.

For earthbound me, sapphire.

For someone rich enough for private space flight, both.

1. Both Hesalite/Plexiglas & sapphire watches have been into space on NASA& Roscosmos missions including a couple of Rolexes, an AP, a Sinn etc. https://www.hodinkee.com/articles/eight-space-watches-that-arent-the-speedmaster-professional
2. Bezos and the other 3 passengers on the maiden manned voyage of Blue Origin wore commemorative Hesalite Speedmasters given free by Omega for the occasion, but this was probably more for the history than any safety requirements :https://www.hodinkee.com/articles/omega-speedmasters-head-to-space-jeff-bezos-wally-funk
3. I'm not sure if Blue Origin let passengers wear their own watches. But... I suppose if you are paying between 300k to 150million for a seat, you get to wear what you want?!? Plus, I think Blue Origin are legally regulated by FAA for safety, not NASA
4. My 2 cents: buy the one you are going to love and wear on the ground the most!

I would do what I did and get a hesalite and then swap out the closed caseback for a sapphire exhibition one from Spiralwinderwatchparts.com

I chose the hesalite