According to Osho, among enlightened Masters there is no higher or lower; in the light all yardsticks vanish. 'Complete incarnation' is not an objective rank but the devotee’s vision: whoever wholly captures your love becomes complete for you. Single-pointed faith leaves no second, so Krishna for a Krishna-bhakta, Mahavira for a Jain—each is complete, though ultimately all Masters are equal.
There isn’t a single “best” Master; the one you love totally is best for you, while all true Masters shine with the same light.