It was the best day of my life.

这是我一生中最美好的一天。

《牛津词典》

This is the best day of my life!

这是我生命中最棒的一天！

youdao

That was one of the saddest days of my life and the best day of my life.

那是我一生中最悲伤，也是最好的一天。

youdao

" He calls the day he finished the book "the best day of my life.

CNN: 'Idol' fans will love 'Better Nate Than Ever'

Ms. ALISON BLANCHARD(ph): I'm Alison Blanchard, and the best day of my life just happened.

NPR: Bang a Can: Auditioning for 'Stomp'

"It was the best day of my life - it was a special moment to score, very emotional, " said the 25-year-old.

BBC: Eduardo delight at dream comeback