I've got almost 1k mp3's on my external HD at work. Once I start getting bored of my current list, I'll go on YT and look up videos that has a compilation of hits of a specific year. I'm old school. I got oldies, 80's, 90's, early 2k, movie soundtrack, instrumental. Always keep it diverse.
New music. I just go to the new music section of Apple music. I also listen to First Take and Undisputed on Youtube. YouTube is good for when you don't know what to listen to. Watch Mojo always has new lists.