I know this is an obnoxious attitude, and I feel selfish saying it, but I'm done waiting.
Every OC version upgrade in the last couple of years broke something, forcing me to either not upgrade, downgrade, or go without basic functionality until some fundamental app (e.g. contacts or calendar) was updated to work with the current OC version. It's frustrating as hell.
I've been using ownCloud for years. I first played with OC version 3, and then properly migrated and replaced SpiderOak with OC version 5. There have been noticeable issues creeping into OC for a while, it's completely understandable why an ownCloud co-founder and the core dev team up and left. In a single year, the Nextcloud server has massively leapfrogged ownCloud in functionality, and the associated NC apps are also multiple versions ahead of the equivalent OC apps. On top of that, the number of apps available for NC are significantly higher than on OC.
I'm done waiting. OC is stagnating. They're closing offices, losing devs, and if I need to stop upgrading ownCloud in order to keep apps working, then I'm stagnating even further. Upgrading to Nextcloud was wonderful. Not only does the server itself have significantly greater functionality, but it has a plethora of apps that you think OC users need to keep waiting for.
The authors have updated those apps, and they updated them for the server that's still being actively developed. Waiting for someone to port the Nextcloud Bookmarks app to ownCloud is folly. I've waited long enough.