There is not a single "best" Spotify equalizer, as it varies according to your headphones and music taste, but a good all-around setting would be to slightly boost the bass (low frequencies), keep the mids balanced, and add a small treble boost for clarity. This results in a punchy bass, vocals that are clear, and highs that are crisp without any distortion, and it is suitable for most genres such as pop, hip-hop, and rock.