Which almanac is the most accurate?

The auspicious part of the "Hee Sa Square Method" calendar was not arranged by the same country, but independently. Because of the different methods, bases and bibliographies of choosing auspicious days, the authoritative book of choosing auspicious days is Xie Fangshu, which was written in Qing Dynasty and titled by Gan Longyu. Almanac, also called old almanac and imperial almanac, is a kind of almanac based on the China lunar calendar.