He is the best person full of excellence and transcendental qualities.
aisvaryasya samagrasya viryasya yasasah sriyah
jnana-vairagyayos caiva sannam bhaga itingana (Visnu Purana 6.5.47)
Bhagavan, the Supreme Personality of Godhead, is thus defined by Parasara Muni as one who is full in six opulences—who has full strength, fame, wealth, knowledge, beauty, and renunciation.
The Lord is the possessor of all these six opulences completely and there is no one who can be greater than Him in all these six opulensces and hence He is rightfully the greatest, the glorious and the Supreme.
lyāṅra bhagavattā haite anyera bhagavattā
‘svayaṁ-bhagavān’-śabdera tāhātei sattā (CC Adi 2.88)
Only the Personality of Godhead, the source of all other Divinities, is eligible to be designated svayaṁ bhagavān, or the primeval Lord.
As mentioned by Chaitanya Mahaprabhu, only a person who is the source of everything in this cosmic world can be rightfully the Supreme. Krishna is the possessor of the six opulences and He is the prime source for this cosmic Universe. From Him comes all living and non living entitites. He is the father the seed giver and so He is glorious and is Sarva Sreshtah.
The Supreme Lord is the cause of all causes – sarva karana Karanam (Brahma Samhita).
Lets chant the Holy Name of the most excellent, glorious personality. Lets strive to spread His glory and always glorify Him with true Bhakti and pure devotion.
Nama 69 – VishnuSahasranama