This largely depends on your personal preference, your natural hair color, and your skin undertones. But as a general rule, we usually recommend going a shade lighter than your natural color as this can help mask gray hair growth more organically. Darker hues tend to cause a stark contrast against gray roots, which makes the regrowth more noticeable.
For warmer skin tones, rich colors like chestnut or caramel might be the perfect choice. For cooler skin tones, ash or blonde tones could be more flattering.