The peak brightness is a meaningless figure just like PMPO used to be in audio long time ago. Most UHD Blurays (barring Batman vs Superman - Ben Affleck's white suit) don't even get to 1000 nits peak brightness. What really matters is how good is the tonemapping algorithm of the TV and how well does the TV preserve highlight detail. In both those things, the LG OLEDs do a better job than anything else out there simply because they do not clip highlight detail and try to preserve the same by tonemapping. Also the LGs are the only ones which have something called "Active HDR" where the display processor actually looks at the static metadata in the HDR10 content and adapts its tonemapping algorithm akin to Dolby Vision (maybe not as good) on the fly for static metadata content. Every other TV does plain static HDR with HDR10 content which is not a great tonemapping algorithm. If you really want the brightest TV out there, it is the Sony ZD9/Z9D but even Sony thinks it is inferior to their own Sony A1 which uses an LG OLED panel.
As for the Samsungs - QLED is marketing spiel - it is nothing but an LED edge lit LCD display. The primary issues with the samsungs are :-
(i) Poor contrast performance in both SDR and HDR content compared to OLEDs as edge lit LCDs will never be able to match OLEDs in this regard. Neither can local dimming LCDs for that matter.
(ii) It does not support Dolby Vision and HLG and they never will support the same as Samsung and Panasonic are planning to launch a new standard called HDR10+ which plans to incorporate dynamic metadata in HDR10 standard
(iii) It has poor input lag performance in case you wish to connect a PC/XBox One X/PS4 Pro
Don't trust my word - trust the experts in this -
http://www.hdtvtest.co.uk/news/category/reviews
Vincent Teoh is an ISF certified professional and does TV reviews for a living.
https://www.rtings.com/tv/reviews/lg/c7-oled comments on two new features for the 2017 LG OLEDs:
1) HDR effect
2) Active HDR with Dolby Vision. Can you explain in simple terms what Active HDR with DV does? If I'm interpreting things correctly, it effectively turns a static HDR source (such as HDR 10) to an equivalent of a dynamic source like Dolby Vision. In other words, it "upgrades" HDR10 content to something closer to a Dolby Vision level of content.
Are these two new features valuable in your opinion?
The HDR Effect picture mode attempts to turn SDR content into HDR content, by radically changing the picture's gamma curve and oversaturating colors near the edge of the SDR gamut. This is similar to Samung's "HDR+ Mode". We don't recommend using it as it makes content quite different from what the creator intended, but some people may prefer it.
It's unclear what Active HDR does, most of the information about it is just marketing jargon. There's no setting on the
C7 to disable it so it likely doesn't do much.
Update 9/4/2017: LG has released a
calibration document for its 2017 OLEDs that gives more information on the 'Active HDR' feature:
"LG’s 'Active HDR' function analyses content on a frame by frame basis in real time, to determine metadata for the scene. This information is then used to adjust the HDR tone-curve to match the content, on a frame by frame basis. Control of the 'Active HDR' feature is found in the 'Dynamic Contrast' setting in the Expert Picture Settings menu. In HDR mode, the Dynamic Contrast settings are defined as follows:
Off - Active HDR Disabled / Contrast Enhancement Disabled
Low - Active HDR Enabled / Contrast Enhancement Disabled
Medium - Active HDR Enabled / Contrast Enhancement Low
High - Active HDR Enabled / Contrast Enhancement High
The default setting of ‘Low’ is recommended for accurate content reproduction."
We don't expect 'Active HDR' to improve picture quality very much, only reducing banding and increasing detail a little by more efficiently using its bits of information.
Don't base your judgement on online reviews only, use them as a starting point, but make your final decision by seeing the Tv set in person and probably with your own content