～に越したことはない（にこしたことはない）

About

The ～にこしたことはない pattern is used to describe that "ideally, one does/doesn't do X", "it's best to do/not do X", or "it's best if X is/isn't the case".

～にこしたことはない statements are based upon obvious information and/or common sense and have a nuance of "obviously, it's best to do/not do X".

～にこしたことはない is most commonly used in casual and polite spoken scenarios.

～にこしたことはない can attach to casual form verbs/い-adjectives or to nouns/な-adjectives using である(こと).

E.g. 億万長者おくまんちょうじゃでなくても良いいけど、お金かねはあるに越こしたことはない。 "You don't have to be a billionaire, but (obviously) it's good to have money."

E.g. そりゃ失敗しっぱいしないにこしたことはないけど、しても死しぬわけじゃないよ。 "Of course, it's best not to fail, but even if you do, it's not as if you'll die."

E.g. 給料きゅうりょうは高たかいにこしたことはないけど、だからといって楽たのしくない仕事しごとはしたくない。 "Ideally, the pay is high, but even so, I don't want to have a job that isn't fun."

E.g. 新あたらしいパソコンは高性能こうせいのうであることにこしたことはない。 "It's best if (one's) new computer has good performance."

Summary

• 

  The ～にこしたことはない pattern means "ideally, one does/doesn't do X", "it's best to do/not do X", or "it's best if X is/isn't the case"

• 

  ～にこしたことはない statements are based upon obvious information and/or common sense

• 

  ～にこしたことはない is most commonly used in casual and polite spoken scenarios