You are trading off power versus control, feel/playability versus durability.
Gut Mains/Poly Crosses - provides more power and the feel/playability of gut
This is my setup, and for me provides the best spin of all 4 for the SAME swing.
Poly Mains/Gut Crosses - provides more control and the durability of poly
All Poly - maximizes control and durability, and arm unfriendliness, and provides the most spin since one can swing faster, generate more spin and still keep the ball on the court
All Gut - maximizes power, feel/playability, arm friendliness, and to some extent limits spin because the faster you swing the less ability you have to keep the ball on the court.