This is largely dependent on the chewing personality of your dog!
Split Chews have the marrow exposed, offering an incentive to the dog and giving quick access to the nutritious, tasty, center. Due to the marrow being softer, and easy to consume, split chews tend to not last as long as whole chews.
Whole chews have the marrow encased by dense, challenging, calcium ring. They are more challenging than a split chew, and tend to last longer.
If your dog has never had an antler before, we recommend starting with a split chew.
If your dog has a history of poor dental health, an antler may be too challenging.