Metro London, the capital of Great Britain has as many accent varieties as the entire U.S. -
not to mention varieties spoken in Wales, Scotland, Manchester, Liverpool, Bristol and beyond.
Thus, Received Pronunciation became a thing (thanks to the BBC and the 2% of native RP speakers).
There is U.S. pronunciation, vocabulary, and orthography. The Mid-Atlantic accent -
is largely a thing of the past, but from Boston, New Jersey, California, Alabama and Texas
there are many local varieties. Standard American, popularized by modern media is associated with north mid-western states.
CANADIAN is a great option for an international audience
(and a personal favourite), it is often said that they speak American but spell like the British.
Perhaps it's because Canada maintains its European heritage more than their southern neighbours, while
influenced by American media.
ENGLISH SPEAKING COUNTRIES
Spoken in many countries in the Carribean, India, Oceania and more.