Horizon is graphically more impressive for what it is. But Uncharted 4 beats it on most sections. Uncharted 4 is on rails and that allows Uncharted to look vastly superior to Horizon in most sections. The details on the rocks and the vegetation which isn't always fully intact and arguably better enemy and player design in general. Horizon does however look miles beyond any open world rpg on PS4, especially when you put it next to Fallout 4, Dark Souls or Bloodborne. Also the water in Horizon is kind of meh.
Please excuse my (probally) poor grammar