I currently own both a sapphire and a hesalite. For me, the sapphire wins. Both are beautiful. Neither is a bad choice. It is very much a personal opinion on which is "better". I find it annoying when someone uses language that makes it seem like buying anything other than the hesalite is for fools. I find at least one such comment in nearly every discussion of it.
For my opinions:
I find the clarity of the dial to be higher for the sapphire. I enjoy watch photography, and for me, the sapphire with AR is much easier to photograph. The hesalite dome seems to always catch a glare and distortion from one angle or another in the photo. I generally prefer watches with strong AR and "invisible" crystals, so it makes sense that the "domed, warm, reflective" hesalite is less of a draw for me. For others, it's a thing of beauty.
The "milky ring" catchphrase is over blown IMO. If only there was a phrase for "countless micro scratches over the entirety of the dial view, not to mention some obvious deeper ones from when I brushed by that door but its ok because I'll spend a few minutes of my day rubbing away the structure of my "crystal" and start immediately collecting scratches again". Obviously that's a ridiculous viewpoint of the hesalite, but it's the same way I feel about "milky ring". Also, why do people bring up scratched AR when talking about the sapphire models? The AR is only on the inside so if it gets scratched, you've had other problems.
For me, what does win for the hesalite, is historical correctness. However, I find the "you don't want your sapphire shattering in space" repeated wisdom to be a bit off as well. What about the sapphire on the Omega X-33 models? Or the Fortis Cosmonaut models for the Russian Space Agency? Sapphire seemed to make the cut there.
This ended up being more a defense of the things I see repeated about sapphire, but I hope it gave a different point of view from someone who is staring at both of them right now.
It's a privilege to own ANY speedy, and you're in a lucky spot to be able to make that choice.