Load Sharing Communication Method

I'd say ethernet is the way to go, but mostly because my limited experience with CAN has been horrifying at best.

Pay attention to your network configuration to reduce the upset caused by communications loss or interruption. The opportunity to monitor the system operation with enterprise analysis software is valuable, but it could expose the control channels to disruption, if not designed carefully.

Conservative design would keep critical control variables off the network, utilizing analog inputs and outputs between the controllers.