Question:Joseph was the favorite of all of Jacob's sons, so why did Judah get the blessing?
There were two things which typically went to the eldest son (not the favorite son): The blessing and a double portion. While it was normally the right of the firstborn to receive these, there were times when the father changed it.
Joseph was Jacob's favorite son, but it was because Jacob's sons had treated Joseph shamefully by selling him off into slavery that Jacob decided to give the double portion, also called the birth right, to Joseph. "And now your two sons, Ephraim and Manasseh, who were born to you in the land of Egypt before I came to you in Egypt, are mine; as Reuben and Simeon, they shall be mine. Your offspring whom you beget after them shall be yours; they will be called by the name of their brothers in their inheritance" (Genesis 48:5-6). He did so by officially "adopting" Joseph's sons as his own. Each son, Manasseh and Ephraim, received a portion of Jacob's inheritance; thus, Joseph's family received a double portion. In a sense, it wasn't totally out of line since Joseph was the firstborn of Jacob's intended wife. Reuben lost the right to the double portion because he committed adultery. "Now the sons of Reuben the firstborn of Israel - he was indeed the firstborn, but because he defiled his father's bed, his birthright was given to the sons of Joseph, the son of Israel, so that the genealogy is not listed according to the birthright" (I Chronicles 5:1). Hence, the birthright was removed from the firstborn of Jacob's first wife, Leah, and went to the firstborn of Jacob's second wife, Rachel.
The blessing was also something given to the firstborn. After a father died, the firstborn was expected to become the head of the extended family. These blessings were also prophecies concerning each tribe's future.
Reuben, as Jacob's firstborn, is referred to as the beginning of Jacob's strength. This is a common view (Deuteronomy 21:17; Psalm 78:51). However, Reuben did not live up to his father's expectations. He was unstable and adulterous. Later, the tribe of Reuben never produced a leader within the nation of Israel. They chose to settle before Israel entered the land of promise (Numbers 32). The tribe was involved in erecting unauthorized places of worship (Joshua 22:10-34). When a call came from Deborah and Barak to repeal invaders, the tribe of Reuben failed to respond (Judges 5:15-16). Truly, the tribe was as unstable as their founder.
Simeon and Levi were notorious for their anger and cruelty. They had endangered the safety of the family when they destroyed the town of Shechem. Jacob prophesied that the tribes who would descend from them would be scattered among the other tribes. Even though the tribe of Simeon received an inheritance, it fell within the boundaries of the inheritance of Judah (Joshua 19:1). Eventually, the tribe of Simeon fades from existence. It was assimilated into the tribe of Judah. The tribe of Levi only received cities scattered among the other tribes of Israel (Joshua 21:1-3). Even though they were scattered, the tribe of Levi did eventually redeem itself in the eyes of God by standing against the idolatry of the other tribes (Exodus 32:26-28).
Judah's name meant praise and he became the object of praise among his brethren. He would be the leader of Jacob's family and his descendants would lead the nation of Israel. Starting with David, all the kings of Israel came from the tribe of Judah. Their rule would continue until Shiloh comes. The word "Shiloh" means "unto him the peoples shall gather" -- a reference to the Messiah. In Revelation 5:5, Jesus is called the Lion of the tribe of Judah. It was from Judah that peace would come (Micah 5:2-5). Jacob also prophesies that the tribe of Judah would become prosperous. Eventually the descendants of Israel are known as Jews, which is a derivation of the name of Judah.
Jacob states the tribe of Zebulun, whose name means "dwell," would settle near the sea. In Joshua 19:11, they were given territory up towards the Phoenician city of Sidon.
Of Issachar, Jacob says he is strong, but lazy and docile. Issachar's name means "day laborer." Good land was assigned to the tribe of Issachar. Their territory included the valley of Jezreel, which was the bread basket of Israel. However, their rich land made them a prime target for the invaders of Israel. They spent much of their time serving other nations.
Dan, the "judge," was a snake in the midst of Israel. It was the tribe of Dan which introduced idol worship into Israel (Judges 18:30-31). When the nation of Israel divided into two countries, one of the two centers of idol worship in the northern country was in Dan's territory (I Kings 12:28-30). Notice that Dan is not listed among the tribes in Revelation 7:4-8.
The name Gad meant "troop." Jacob predicted that Gad would be invaded, but it would be able to repel the attack (I Chronicles 5:18; 12:8).
Asher, whose name meant "lucky," also gained rich lands in the promise land (Joshua 19:24-31).
Naphtali would be known for swiftness and fine compositions. Barak who lead the army for Deborah was from this tribe (Judges 4:6, 10, 15; 5:18).
Joseph's descendants would be strong and numerous. God's favor would be upon them; He would nourish and protect those who descended from Joseph. They would receive the blessings of heaven, the seas (the deep, which is a male noun in Hebrew), and the womb. In other words, they would be blessed with numerous children.
Benjamin would be successful in warfare, but would also be known as cruel and voracious (Judges 20). The first king of Israel, Saul, was of the tribe of Benjamin.
So in the case of the blessing, Jacob had gone in the order of birth, but he skipped over Reuben, Simeon, and Levi because they were unsuitable to become the head of the family. Judah was next and that is why he received the blessing.