Was the Eastern or Western Church more to blame for the Great Schism?

The two parts of Catholic-Orthodox Christianity always had different ideas of Christian worship and even celebrated Easter at different times of the year. So we should not look for "blame" in the Great Schism of 1054, when it may have been inevitable. Certainly there is no real evidence that the Schism did long term harm to Christianity.

The Council of Nicaea, called by the Roman Emperor Constantine in 325, decided that Christianity in the Roman Empire would be led by four senior bishops or Metropolitans representing Rome, Alexandria, Antioch and Jerusalem. The Council also made provision for Constantinople and Carthage, where Metropolitans were subsequently appointed, although the role was short-lived in Carthage. Thus, religious authorities in the mainly Greek-speaking eastern regions held that the bishop of Rome was one among equals. However, the bishop of Rome, designated as the Pope, insisted that he had greater authority than the other Metropolitans. Gradually, differences built up until, in 1054, Pope Leo IX insisted on the right to make a change to the Nicene Creed, on his own and apart from an Ecumenical Council. The Great Schism resulted when Pope Leo IX and Patriarch Michael I excommunicated each other.