The American KB swing is widely used in CrossFit, though the historically more popular Russian swing is making a comeback in CF gyms. They both have their value, and the American swing is the standard in competitive CF, but there are a few things to consider when choosing which is the right swing for you. Strength coach Gray Cook was recently on Kelly Starrett’s Mobility WOD where he discussed some important points regarding each:
It is audio (and a couple minutes long), but I highly recommend it if you have some spare time.