According to Osho, a 'best friend' is not a rank but a quality of totality: if someone is truly your friend, they are your best—anything less isn't friendship. Friendship admits no hierarchy or comparison; each friend is met with whole-hearted presence, sincerity and uniqueness. Thus he has only best friends, making choice among them both unnecessary and impossible.
A real friend is always your “best” because friendship isn’t about comparing people—it’s giving each friend your whole heart.