In terms of the most balanced in speed, consistency in page rendering and good default settings, is there a clear winner?
Personally I've been using both Dark Reader and Midnight Lizard on different devices and I can't say I noticed much of a difference in terms of performance, what I did notice is that Dark Reader seems to have better defaults, but many complain that it slows down page loading a ton, I haven't heard the same about Midnight Lizard, but maybe that is by virtue that it has way way fewer installations and therefore fewer people talking about it.
Do you know if I've missed one and there is a totally different extension that does even better than both?
On mobile I don’t think there’s any other way, on desktop you can use the crude background/foreground color changer in the settings. I think only Chromium implemented an embedded dark mode as of today