I have a 4K 120hz OLED TV. The difference is quite drastic compared to my old 1080p LED. It's certainly sharper, and probably the practical limit. I've also seen 8K, and, meh. I don't even care if it's noticable, it's just too expensive to be worthwhile. We should just push more frames and lower latency for now, or, the Gods forbid, optimise games properly.
Ehhhh, I think 1080p is definitely serviceable, it's even good enough for most things. However, I think 1440p and 4k are both a pretty noticeable improvement for stuff like gaming. I can't go back to 1080p after using my 3440x1440 monitor.
I've heard recently that there's "cheap OLED" and "expensive OLED." Which one did you go for? I've got a 75" 4k OLED for $400 and it's definitely super dark. I can't even watch some movies during the day if they're too dark. The expensive ones are supposed to be a lot better.
I've got an older Sony bravia A9G and I've seen reviews complaining that it's too dim but I've had no issues. I think some people just have really poorly thought out tv placement, or overly bright rooms. Also just close the curtains if the movie is dark...
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Too expensive both in terms of the price, and the massive amount of storage needed for 8k video. I don't really think 8k is ever going to be the dominant format. There's not really much point in just increasing resolution for miniscule gains that are almost certainly not noticeable on anything but a massive display. Streaming services are going to balk at 8k content.