This was a hard question. I chose cartomancy, just for the boring reason that I use it the most so therefore it has statistically given me the most number of accurate readings.
But I have had a lot of success with astrology (even though I'm not great at it), runes (which I've only done a few times), palmistry (which I did a lot as teen and in my early twenties), dream interpretation (which can be the best method overall *if* you happen to have an important dream, which happens only occasionally for me).
I have not gotten anything out of trying tea leaves, but one time I had some coffee grounds that I saw an accurate message in; I wasn't trying to do divination, though. I just drank my coffee and there it was at the bottom of the cup. There aren't even that many grounds in most days.