20/20
92"
1920x1080
143.5" (I sit at 135")

This uses the old 60 pixels per degree for 20/20 vision.
(To calculate pixels per degree for 1080p -> Distance * 38.45 / Diagonal size)

It has already been proven that the human eye can benefit from better pixel density all the way up to 200 pixels per degree (That's where double blind tests turn into pure guessing at which has better picture quality) It's not about not being able to see individual pixels, but about seeing a smooth picture with no traces of the pixel grid.

In my experience going to between 100 and 120 pixels per degree gives a great picture. Still needs some AA but it looks almost life like. Sit twice as far away as this calculator suggests for best results, or enter 20/10 vision.

Still amazed everyone has "Normal Vision", surely someone can boast 20/15 vision or better.

20/20
47"
1920x1080
73.4"

I don't doubt that th ehuman eye can probably resolve better than what this chart may suggest. But I sincerely feel that if you stay at the suggested distance from the screen (in relation to your screen size and resolution) to be able to make out the pixel grid on your display becomes very tasking. Like in my case I have to start focusing into a super specific area on the screena and squint..... I strongly doubt anyone uses their displays like that.

My vision: 20/15 (last checked a couple years ago as part of a regular maintenance after eye surgery...I'm pretty sure it's still the same)
TV/Monitor Size: 42 inches
Resolution: 1920 x 1080
Recommended Distance: 87.3 inches
My actual distance: About 2-3 feet (24-36 inches)

I use a 42 inch LED TV as my computer monitor and also have 4-5 game consoles hooked up to it. I tend to lean back in my chair when playing a console game or a PC game that fully supports a controller, but I'm right up there with my keyboard and mouse when playing an FPS or something. So that's why the variation in my viewing distance.

So needless to say, I can easily make out pixels and can easily make out the difference between 1080p and 720p. I would go with a 4K TV but I'm having a hard time finding one as small as 42 inches.

Wow, you have a massive TV! A 100 inch TV won't even fit in my room!

I wouldn't be surprised if I actually have like 20/18 or 20/15 vision lol..... if my time in military school and my range scores are anything to go by, but we were never rated higher than 20/20 so I could never actually tell.

20/20 (I think?)
75" screen, more or less (projector).
1080p

Viewing distance: 3m

My actual viewing distance is 2m, so yes, unsurprisingly I can tell very well when something is 720p (it's fugly).