But given all the makers and more I've yet to find anything beyond the basics.

For example brightness of 300 cd/m2 (or 300 nits) gives us a measure of light output for a display but given the tricks of extending the contrast range by dimming the LCD backlight, you can't be sure it's native or assisted by backlight dimming.

Best move is to read CNET reviews and see the set at the shops.