I use two types of tracks:
1- Solo grand piano recordings of pieces my father used to play on the Steinway grand piano at home. Mostly Lizt, Chopin, Rachmaninov
My ear is fine-tuned to that instrument, and I can tell when something is wrong (or better) with the setup.
2- Various tracks from Steven Wilson albums (usually 5.1 or Atmos)
These are Prog rock music, mostly instrumental, with a wide dynamic range and extremely well recorded and mastered. Some push the low end hard, others are massively layered and are great at showing if the system can fully resolve the mix or if it turns to a mush of sound.
The last one, and orchestral music at peak can clearly show if the room is treated right or not. Untreated rooms ring, have peaky bass, and sound turns to mush at higher volumes.
So, in general, pick music that represents a familiar baseline with roots in the real world, along with well-recorded music with enough complexity and dynamic range to exercise a system fully.
A good setup should shine on ALL types of music, not just one genre or class of instruments. And do so at varying levels of loudness.
For instance, my system gets solo and orchestral piano right, but it can also rock down the house at 100+dB with Prog Rock or Dance music.