Classic set. No matter what other options exist I will always have a pair as they were my first pair of decent headphones, and having them for years they're extremely familiar sounding to me, so if i just need to know what something sounds like without having to think about it I still reach for these a lot because I know how they're gonna sound with what I'm listening to. If you have these for years, then the same thing may happen to you even if you get other headphones in the future. Congrats!

And as for what you should test it out on, test it out on a song with some sort of sentimental meaning to you. It could be a song you heard on the radio as a kid at a certain time or something from a movie that left an impact on you or whatever, just find the song that means something to you. Sometimes, with a decent set of headphones, you hear things in that song that you didn't hear before and it makes it feel like you're listening to it for the first time again. When you find the right song played on the right headphones, it's an incomparable feeling.