1. The Beatles (active 1960-1970): Considered by many to be one of the greatest bands of all time, The Beatles' harmonies and blend of diverse vocal styles were groundbreaking and influential.
2. The Beach Boys (formed 1961): Renowned for their "California Sound" that combined vocal harmonies, catchy melodies, and surf-inspired themes.
3. Motown Vocal Groups (e.g., The Temptations, The Supremes, The Four Tops): Motown Records produced multiple legendary vocal groups with soulful and harmonious vocals.
4. Take 6 (formed 1980): An a cappella R&B group praised for their jazz-influenced arrangements and seamless vocal blending.
5. ABBA (active 1972-1982): Renowned for their infectious pop tunes with distinctive vocal arrangements and harmonies.
These vocal groups have had significant cultural and musical impacts. However, determining one definitive "best" vocal group universally would be difficult due to personal preferences and diverse musical styles.