I'd like to suggest our own Greybird Geeko theme as the new GTK theme for Xfce, which was introduced to Factory a month ago .
The theme started as a modified version of Greybird by the Shimmer Project  with some small openSUSE branding elements, but it gradually introduced several fixes and features, including a highly requested Dark variant of the theme.
Reasons for Greybird Geeko to be default:
1) Greybird is arguably the most complete GTK theme for Xfce as it is maintained directly by Xfce developers.
2) Greybird Geeko  adds our own touch to an already great theme. It is maintained and developed directly by us although we collaborate closely in the Shimmer Project with Greybird, as well as elementary-xfce icon theme.
A lot of effort was put in this theme and it makes sense in my opinion that we give our own identity to openSUSE Xfce. Thus I would like this to become default by the introduction of Xfce 4.14 next month.
 https://lists.opensuse.org/opensuse-factory/2019-06/msg00231.html  https://github.com/shimmerproject  https://github.com/shimmerproject/Greybird-Geeko