I always buy the Belkin screen protectors from Apple Store with in-store installation whenever possible. It’s an absolute no-brainer.
Yes, I can get a proper pair from Amazon for 15-20$ (I prefer amFilm OneTouch vs Spigen EZ FIT) and they are equal in terms of quality. These good ones also come inside a proper plastic frame - not the crappy drop-in ones, but the frame with the protector already inside, that you clip on top of the phone for perfect alignment. On paper those should provide decent installation results, but no matter how I try, there always will be 1 or 2 pesky dust particles in a form of tiny hairs. And I usually go over 2-4 protectors before I even reach that. It wastes 10-30 minutes of my life, and makes me want to throw my phone out of a window by the end of it. I truly, truly hate the process! I hate the bathroom steam-up, I hate the dust stickers, I hate the dust blowers, I hate examining the screen and finding a tiny black dust hair after thinking that you finally succeeded.
With Apple Store version you get a protector that is compatible with the Belkin installation machine, which has an anti-dust brush that swipes the screen as you pull away the plastic film. This makes it possible to achieve 100% dust free installation.
It’s still possible to get a small dust spec trapped, because a lot of the store employees aren’t careful enough, don’t know how to do it properly at all, or simply don’t give a shlt. But they’ll re-attempt the installation for free with a new protector within reason if you’re not happy. Some will try to brush you off with the typical “we don’t reinstall unless bubbles appear or it starts to detach”, but that’s BS. These glass protectors never bubble or detach unless the dust spec is truly massive.
So basically it’s the only viable way to achieve 100% dust free installation, and it saves me a lot of nerves. But I want perfect installation and dust particles annoy me. If you don’t care or live in a class 10 cleanroom, get the ones from Amazon and save a few bucks.