We've used both. Orijen is rich enough to cause loose stools, and Wellness definitely gave them the worst runs ever. Orijen is one of the best kibbles, so we still feed it, but blend it with Wellness CORE. The CORE solidifies their stool, and they love the flavor. We also blend in Acana lamb. They didn't do well on Wellness, and Orijen by itself loosened up the poo.