None of them. It seems to be a lot of work and I don't see much benefits since I'm understood anyway. Actually most people I know don't bother. I wonder how common it is for someone to try and sound like a native speaker.

really I don't know what the best , but of course it depenede on you, for inctance; if you want to immigrate to Australia you need to learn their accent and so on , choose what you need , but if you don't need any sellect what you like