Ever wondered how they really compare? Here is a side by side comparison. I’ve put the screen protectors against my monitor with a white background. You can see that the blue light filter gives a more yellow-ish tint while the privacy filter steals a lot from the brightness.
Of course, do note that these are not attached directly on a smartphone’s screen. And the protection layer is still on it, so it’s extra thick and may distort it further. This is just to give you a general impression.
I’ve had the blue light filter screen protector always on my FP4 and it was good. In direct sunlight it could get a purple glow sometimes. I now use the privacy filter one and when applied it’s not that dark at all. So I don’t think you can go wrong with any of them. But if you don’t want to lose any brightness at all, then I guess you’re still most safe with the blue light filter one. Also, the privacy filter gives a bit of distortion to the resolution, even when directly looking into the screen protector.
So I would rate the blue light filter as a 9/10 and the privacy filter 8/10.