This is the Proprietary cabling mechanism and is limited to distance. The advantage of Stackwise over VSS is that you can add/stack around 9 devices at one go.Were as you cant do the same with VSS.
VSS (Virtual Switching System):
VPC (Virtual PortChannel):
MLAG (Multichassis Link Aggregation):
MLAG is the ability of two and sometimes more switches to act like a single switch when forming link bundles. This allows a host to uplink to two switches for physical diversity, while still only having a single bundle interface to manage.
For access layer when I have only 3750 stackable switches I cant do VSS or VPC on that hence would be using stacking and connecting them together to have single access.
VPC is best but you need to have Nexus device if you want to use this feature.