RoRo wins on price and frequency. Container wins on protection, flexibility and the ability to ship personal effects legally inside the vehicle. The right choice depends on what you're shipping and where.
Choose RoRo if: the vehicle is a standard daily-driver, you want the cheapest option, the destination has a frequent RoRo schedule, and the vehicle is fully running with no personal effects inside.
Choose container if: the vehicle is valuable, rare or non-running, you need to ship personal effects with the car, the destination has limited RoRo service, or the vehicle is an EV requiring battery-specific handling.
On insurance, container shipments are easier to underwrite at higher declared values. Some marine insurers won't cover supercars or classics on RoRo at all.