American, British, Australian English: the Differences

Are you now learning English as a second or foreign language? Along the course of learning process, we might find English relatively tricky especially after we find out there are more than one variety to distinguish and learn. For the record, there are so many English variants spoken in different parts of the globe. There are American English, British English, Australian English, Singaporean English, Indian English, etc. Some English learners regard this as their  learning hindrance. This diversity obviously leads to a number of arising questions that actually reflect how confused English learners. Students often ask, "Which variety to learn best of all?" or "Which English is better?" or "Which one is more internationally acceptable?". I'll leave the questions unanswered because each of the answers depends on varied factors.