What is the best and most accepted halachic book to study Jewish law?
The Chafetz Chaim's Mishna Brura is clearly the most accepted among ashkenazim, although some prefer his contemporary's R. Y.M. Epstein's Aruch HaShulchan, which is more lengthy, "maverick" and often more lenient. For sfaradim it's less clear, for some follow the readily available R. Ovadia Yosef's Yalkut Yosef, while others consider him to be too innovative and lenient, and prefer the Chida's Birkei Yosef, the Kaf HaChaim or Rav Mordechai Eliahu's Kitzur Shulchan Aruch. Nevertheless, the highly recommended and most "learnable" work, which encompasses the different opinions for ashk. as well as sfarad., and especially deals with the modern questions which are extremely relevant and necessary (and is even translated to English), is Peninei Halacha of Rav Eliezer Melamed.