that's mostly the content, not the renderer making things look so nice
I don't think so. I have for the past year and half been trying to decide what game engine would be best to create a game in. I have used the UDK, Unity3D, and Cry Engine 3 Free SDK, I created a model in blender and added in nice textures and materials, and it looked well. I first imported it into the UDK. It looked fine but it wasn't the best. Then I imported it into the Unity. It was pretty shitty. I am not sure why, but it was. Then I imported it into Cry Engine, it was beautiful. It actually looked better then when I first made it. Keep in mind, I did try everything to make it look nice in all engines. They just didn't come out as nice as it did in Cry Engine.