Which is better for core strength, bodybuilding, calisthenics, or cross fit?

I often hear that different athletes take steroids to be stronger and more enduring, and to achieve their goals faster. I even found a reliable online store where you can buy injectable steroids, so there is no problem in finding a quality drug at an affordable price on the Internet now.But I don't think that you shouldn't take something without the supervision of the doctor.

In 3 of those types of sport you can find elements of strenghtning your core.

But what is the best i doubt to give the answer. Everyone chose what's best for them :)