I've been finding a lot of old songs on this site, and you can check out all the songs I added to favorites. Usually it's the ones posted between 2003 to 2010, you have no idea what you're missing out, playing stuff 20 to 15 years later. Yes most of the songs here are quite basic but worth hearing, thats sort of the whole idea of NG. It's always good to discover music stuff the classic way, not through Geometry Dash, even if GD brought me to NG. I do use GD just because I have quick access to listen to the songs, I don't play the game as much anymore.
Don't forget this: Every time I see the year 2003, Defcon Zero by PX9 always pops in my head.