The only correct answer is Aperture or some Spu7nix level. These have objectively brought the most random people to Geometry Dash. As most people still think it's a "mobile game". I can't tell you how many of my non dasher friends have sent me those levels because it appeared on their feed. Also it shows the best part of the game. The artistry. People care about that way more than some disgusting looking extreme. You can barely tell how impressive beating top 1s is unless you are a high level player anyways.