Like makaikhaan I also find the Turks stupidly easy these days. The trade income is enormous. Though the same argument can apply to any faction that dominates the region such as the Almohds, Egyptians, Byzantines etc.

To make the campaign more challenging I tend to only conquer as far as Tripoli and Leave the Egyptians with Palestine, Egypt, Arabia and Sinai. I then turn on the Byzantines sooner and try to take and hold Lesser Armenia and Georgia.