'No regrets' — comprehensible, but stiff. There's a better idiom.

What a Japanese person actually thinks
Reads like a headline or a slogan on a sports towel. Punchy but not deep.

Literally: regret + none
Actually: 'No regrets.' The なし ending is a clipped literary negative — fine on a banner, a bit terse as a considered statement.

Naturalness●●●●●

Correct and used, mostly in headline-style writing rather than prose.

Coolness●●●●●

Four characters, two of them hiragana. Reasonably balanced but not monumental.

lowWriting なし as 無し here is a common non-native over-correction. Keep it in hiragana.

悔いなし kui nashi
no regrets

The more idiomatic phrasing — 悔い is the felt regret rather than the abstract noun. Shorter and warmer.
一片の悔いなし ippen no kui nashi
not one fragment of regret

The full dramatic version. Long, but it's a genuinely famous line and it carries real force.

後悔なし

Orientation: vertical

Brush.