It depends what your aim is.I personally don't think that the person's origin is the main thing but whether you feel comfortable talking to them. IF you want to improve you need someone who is patient and can correct your mistakes without making you feel bad, or someone who you enjoy talking to.If you don't enjoy it you will not improve or make progress.If you talk to someone who speaks your language you will probably "cheat" and go into your native language but if you speak to a foreigner you will have to talk in English so that is an advantage.