In American English, we use both. It's just a matter of preference. Note that for emphasis, we might use each word as in "He is not going!" Emphasis on "not". Best, Martha

"He's not going" is much more informal in context.

Thank you very much.I found your answers useful.

People use either way, but if you want to emphasize the subject say, "HE isn't going." But if you want to emphasize the negative aspect of the sentence say, "he's NOT going."

Where I live people use ‘he/she isn’t’ more often. But I certainly hear both used often in conversation, and I think either would be fine for informal conversation.