I've been using both LE (LibreELEC-S912.arm-126.96.36.199-444-1000nits) and CE (nightly and stable builds) regularly on a daily basis for a while now on 2 S912 boxes.
To say that CE is is almost not stable and faulty is perhaps a little strong.
In terms of general picture quality, LE scores higher, especially when it comes to OTA SD content, where the picture is sharper and colours more vibrant. However CE continues to show great improvements and recent nightly builds bring the quality much closer.
LE has issues with HEVC content where playback starts but within a few seconds can cause a blank screen, requiring either a scrub to the end of the video or a reboot to resolve. CE does not have this issue.
General playback of the vast variety of video formats is consistently good with both but when it comes to things like Sony_4K_HDR_Camp and many other test files of the same type, LE plays perfectly but CE, in any form shows distinct stuttering, so there is absolutely no doubt that under the same conditions, using the same box, LE beats CE for such very high end video, although it should be said that the general availability of commercial release movies/TV shows using the high end settings of the test files is probably minutely small, so not necessarily a great issue for now but something for the future.
This difference could of course may be related to either CE or LE directly but perhaps to Kodi, where for my use, I am essentially using 17.6 on LE and 18.x on CE, which will still be prone to bugs until 18 becomes an official stable release.
The only area where neither currently works for me is with regards to commercial 4K releases, where I find things too dark in comparison with 720p/1080p versions, so stick with these for the time being.
I do think that to some degree, a form of competition gets created when both comparing the two and giving feedback that can sometimes render some form of hostility, which is a shame because I believe that most people just want to give constructive feedback to aid, rather than hinder development.
The vast majority of users appreciate the work that goes into development and perhaps that also gets a little lost in the conversations, where devs perhaps feel as though they are being jumped on rather than being supported.
We are all most certainly in a far better position than if such endeavours were left to hardware manufacturers, that consistently provide sub par software out of the box.
I am a very happy camper with what is available, as I believe that most of us are and should be.