* 运 (yùn) - This is the most common way to spell luck, referring to good fortune or destiny. It is often used in phrases like "好运" (hǎo yùn) meaning "good luck" or "运气" (yùn qì) meaning "luck."
* 幸运 (xìng yùn) - This literally translates to "lucky" or "fortunate" and is a more specific way of expressing luck.
Therefore, the best way to spell "luck" in Chinese depends on the specific meaning you want to convey.