To answer your remaining question:
Helium is slightly easier to compress. Going from 1 bar to 300 bar at 20 °C the density of hydrogen goes from 0.08 to 20.8 kg/m³ (250x higher), helium is 0.16 to 43.2 (263x higher). In other words, the compressibility factor is slightly higher for hydrogen.
To answer your remaining question: Helium is slightly easier to compress. Going from 1 bar to 300 bar at 20 °C the density of hydrogen goes from 0.08 to 20.8 kg/m³ (250x higher), helium is 0.16 to 43.2 (263x higher). In other words, the compressibility factor is slightly higher for hydrogen.