Now that is a very difficult question. There are many accents in English and even dialects, although almost everyone understands and can speak Standard English, the English we learn in school and that you learn as a foreign language. Probably it is best to either keep to British English, the sort of English you hear used by newscasters, the Queen, etc., or to do the same with American English. You may become confused if you try to learn these two forms at the same time; there are small differences between the two. British English sounds "posh" and formal to most users of other forms of English, even the Americans. American English is much more common, because there are something like 4 times as many people who speak American English. Why have I said nothing about the other forms? This is because they are usually spoken by fewer people - I am not saying American or British English is "better", that would be silly and just annoy other users of italki!

australian ;)

American ^)

Well... It pretty much depends on your taste. Some people may like South African accent, others may love Australian, British, Scottish, etc, etc. I have my preferences though, yet it amuses me and definitely enjoy listening to certain accents spoken in certain countries. It is exactly as if I ask "which is the best accent in Spanish? También tengo mis acentos preferidos. ;-)

I like y'all's. Chilean.