Which English should we learn, American English or British English?

In the process of learning English, I find many words have two pronunciations sounds: American pronunciation and British pronunciation. As foreigners, which English should we learn, American English or British English？ Can you tell me?

(Your last sentence needs to have agreement in singular/plural between your noun and your pronoun.  Either use   "As a foreigner ... should I learn ..."  or "As foreigners... should we learn ..."  )