Which one is correct, "best wishes to you" or "best wishes for you"?
Best wishes to you is correct. I've never heard a native English speaker say "best wishes for you", and there are no examples of "best wishes for you" in the British National Corpus.
- ".. best wishes to you..."
- "best wishes for your..."
In the first instance, towards is the connotation that to is meant to take. (It so happens also to be an annotated meaning.)
In the second, for has no connoted sense of directionality but, instead, connotes application or bestowal--hence the change to possessive of "your..."
In one instance "wishes" extend towards the second person; in the second to something possessed or conferred by the second person.
Word meaning, not grammar, is the more fitting tag. Possibly syntax as well.