Geomancy is in my experience the gold standard for yes/no divinations. I get the same sort of crisp, no-nonsense results from horary astrology, but it's not anything like so easy to learn. Ogham, Coelbren, the runes, and similar systems of sortilege (that's the fancy technical name for oracles where you draw one or more items from a fixed stock of symbols) can be very precise for some people, not for others. Tarot? In my experience, it's an extraordinary rich and flexible oracle if you want to see the whole picture, but you won't get a straight yes or no from it for love or money.

There are tens of thousands of other divination systems out there, most of which I haven't worked with. Some of them may be as good at yes/no questions as geomancy, for all I know.