The idomatic and correct usage is best of luck. It really is short for I wish you the best of luck. Thus, you see why the of has to be there. The best of is a standard construction, e.g. make the best of it.
What’s another word for Best of luck?
Synonyms
break.stroke of luck.blessing.windfall.good luck.fluke.godsend.serendipity.
How do you use best of luck?
Best of luck is often used by itself or in the phrase “Best of luck to you.” Best of luck is used to give both genuine support, as well as to suggest that a situation seems hopeless. Example: Best of luck to you in the job hunt!
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