What are the best excercises to get a 6 pack?

I went 3 months doing sit ups/ crunches and such everyday and then for some reason I stopped for about a month. I have recently started doing them everyday again. I am a very fit and sporty person I enjoy any sort of exercise so I don't have to lose weight I just need to tone.
What are the best excercises to get a 6 pack?
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