I am biased heavily towards EDM / electronic / house / techno, below are my recent go-tos within the genre. Obviously one would want to test more than just within this genre alone, only sharing these since it's my specialty and since regardless of preference they tend to showcase low end very nicely
1. Charlotte De Witte - Apollo (Showcases "thickness" or lack thereof of sub bass)
2. Joseph Ray - Room 1.5 (Showcases soundstaging, density-of-ambiance)
3. Arthur Robert - Kinship (So, so, so many layers - Some headphones you'll uncover new elements, some headphones you'll think they don't exist)
4. Alignment - Old School (Showcases slam, impact)
5. Martin Garrix - Starlight Keep Me Afloat (Very-well-done pop-EDM crossover mixing, showcases how layered pop elements interact with slammy low end)
6. &ME, Rampa, Adam Port, RY X (Showcases vocal precision)
7. Victor Ruiz , Thomas Schumacher - Wonder (Showcases low end, a a perfect example imo in why the Audeze LCD X low end is unmatched)
8. Eynka - First Light (Production goes from narrow to wide soundstage and back, a good way of measuring how wide it goes (for example these sound great on a Hifiman Arya))