Did not know this. Thanks!
Looks like Kiteworks invested in OwnCloud in 2014 and they still seems to be going strong with the OSS development which is a good sign.
This probably explains why there are so many active devs on the project and how they got a full rewrite into version 4 relatively quickly.
Already seems to have more features than Seafile.
Also looking through some of the issues and comments on github about no plans to implement basic features (file search on the android app) does not inspire confidence at all. One of the reasons I'm hoping the OwnCloud rewrite is good.