Really depends on what qualities you regard as 'best'. For cosy reading on a Kindle, the Penguin edition by J. A. Underwood should be just fine. As is often the case, some parts of the original are missing. But at least there's an introduction and a few notes on the original text. Freely availabe (via Google Books) is Monte Adair's translation, originally from 1986 and advertised as 'unabridged'. Seems alright.
Proper scholarship would require a lot more footnotes, of course. Worth mentioning perhaps that hardly any native speaker today can read the 'German' original without difficulty. After all, it’s quite … dated. Literal translations thus run against readability. Probably not what you're after?