に越したことはない|にこしたことはない

1. 1It is best or most advisable to do X, even if it is not absolutely necessary.Ex. 1
2. 2With adjectives or nouns, X is preferable, so the more X the better (e.g. 安いに越したことはない).

Neutral in register and common in both conversation and writing, especially when giving general advice, precautions or common-sense recommendations about health, travel, money or safety. Unlike べき, it does not express duty. Unlike に限る, it is less a personal conviction than a cautious "it can't hurt."

• に限るN2When 「に限る」means 'is best,' it makes a decisive judgment based on personal experience, with a firm tone and no nuance that 'it's fine even if you can't do it.' It also has a restrictive meaning of 'limited to...' (often seen in rules and notices), which 「に越したことはない」does not have.
• ほうがいいN5「ほうがいい」usually attaches to the た-form to give direct advice to the listener, and can also express a preference in a comparison. 「に越したことはない」mostly states common sense, and even when used for concrete advice it is more objective and tactful, carrying the nuance that not doing so may still be acceptable.
• ばいいN3「ばいい」attaches to the conditional form and points out a workable option, emphasizing 'this would be enough'; 「に越したことはない」states the common sense that something is 'of course best.' The nuances differ, so they should not be swapped. 「ばいい」can also express a wish or regret, or ask for a solution.
• には及ばないN1When 「には及ばない」means 'no need to,' it indicates there is no need to do something—the opposite direction of 'it's best to do it'—so the two cannot be swapped. It is formal in tone, attaches only to the dictionary form of verbs or to nouns, and also has the meaning 'cannot compare to.'
• べきN3「べき」is the speaker's subjective claim based on reason or obligation, with a firm tone, and can act as a modifier in 「べき＋noun」. 「に越したことはない」only objectively states that 'this is best,' implying that not doing so may still be acceptable. Swapping them makes the tone stronger.

Unlike に限る (the speaker's firm view that X is the very best) and ほうがいい or ばいい (direct advice, or a way to reach a goal), に越したことはない gives cautious general advice that X is preferable though not essential. It is also unlike べき, which expresses obligation, and roughly the opposite of には及ばない, which means there is no need to do X.