I've had both Rhino and Line-X in previous trucks. Current truck has the RAM factory spray-in liner.
Between the Rhino and Line-X, the Rhino did a better job of keeping stuff from sliding around, and was a little gentler on things that did slide around some (furniture, that sorta thing). But it damaged a little more easily. Sharp edges would cut through it pretty easily to the metal underneath. Didn't happen often, but did happen.
The Line-X was more durable in my case. Never saw any damage on it at all. But it was more slippery, as others have said. The load slid more easily, and I even managed to fall on my own backside once or twice. Scuffed a couple of things I carried that slid more than they should have. My mistake for not securing them better.
Overall, both are excellent products, just slightly different. I'd put either one in my truck again. Pick the one that fits your use-case better.