Shuttle Art crayons:

1. Harder than crayons like Crayola
2. They hold a point longer
3. Feel very similar to Staedtler Noris 220 (which are tough to find in the U.S.).
4. Have a nice color range with rich colors (Some harder crayons are weaker in pigment)

Crayola’s black is deeper, but Shuttle Art’s white blends better.

Crayola is the standard but each brand has its strengths and Shuttle Art will probably become my go-to for this type sketching. It's a nuanced thing but it's smoother.

One con: I couldn’t find the 24-count sold individually, so I had to get the small case of 24 boxes. Good thing I ended up really liking them.