I prefer virt-manager to Cockpit's VM management, way more feature complete.
Cockpit is not ever going to be as good as using the underlying tools it integrates with, but it is still pretty nice for what it is and I like having it.
Cockpit is definitely nice, but it still feels pretty incomplete compared to virt-manager.
virt-manager appears to still be developed, though, just without the same blessing/level of support from Red Hat.