ときが一番

the most when

→ 時
phrase Rare #24,257
the most when Used to say that something is at its highest or best during a particular time or situation. The phrase before とき describes when this is true.
JA: 朝ごはんを食べているときが一番元気だ。
EN: I have the most energy when I’m eating breakfast.

彼はと一緒ときが一番楽しそうだ

He seems happiest when he's with his grandchildren.

ギター弾いてるときが一番幸せかも

I think I’m happiest when I’m playing guitar.

走っているときが一番幸せだ

I’m happiest when I’m running.

子供って泣いてるときが一番かわいいよね

Kids are at their cutest when they're crying, aren't they?