I don't have a clue what type of music you listen to most so I'll spare you another arbitrary recommendation. But some of the comments above are excellent and I will try to add to them.
What I used to test speakers (in my home) are chosen from the music I listen to all the time, enjoy the most, and are recordings with which I am intimately familar. Some will be SOTA recordings (not many), some not (mostly), some recordings that are borderline in some respects but otherwise very enjoyable.
Jax 2 is right on regarding the using of a drecky recording but I do find it useful have recordings which I find very enjoyable but have recording issues that become too prominent on some components/speakers, often found in the reproduction of the upper mid range/highs common to some brass, pianos, and cymbals in a drum kit for example.
I don't usually use SOTA audiophile recordings (although I have a couple which will really test a system which) because unless you are very familar with the contents they tend to make even ordinary stuff sound better than it is when you play normal stuff. And I do, usually select recordings of solo instruments, vocal, and/or small groups, as there is nothing much to hide faults, whereas orchestral recordings or recordings with amplified instruments can cover a lot of sin.
Hope that helps a bit......