I've come to quite enjoy Rancher products. I think the work they are doing is fantastic and lowering the bar for entry into Kubernetes, especially for on-prem/bare metal. Just deployed 4 production RKE clusters on bare metal and also using K3S.
It really transformed my company DevOps. I´m VERY happy. If you can, use Rancher. It is just perfect!
At first look the numbers in the colourful table near the end, Piraeus/Linstor/DRBD seems 10x faster than Longhorn 0.8. The article goes into great depth of the (a)synchronous replication options of Piraeus, but doesn't mention that Longhorn always does synchronous replication. I wonder why?
SUSE being full into btrfs and CEPH, I wonder if they will allow Yasker https://github.com/longhorn/longhorn/graphs/contributors to continue developing. At Kubecon EU & US 2019 https://youtu.be/hvVnfZf9V6o?t=1659 Sheng Yang explains how he tried to make Longhorn first class citizen Kubernetes Storage.