noun which may take the genitive case particle 'no'
best ... of one's life
Used as a prenominal modifier (adj-no) to describe the best experience, event, or thing in someone's life so far. Often contrasted with 人生最悪.
Antonyms: 人生最悪
That trip is the best memory of my life.
He had the best day of his life.
Antonym: means 'worst ... of one's life'.
worst ... of one's life
Compound of 人生 (life) + 最良 (best, finest).