The solver writes element results such as stress/strain in element coordinate system for each element, and nodal results such as displacements in nodal coordinate system. By default the results will be in layer coordinate system. Layer results are written in layer coordinate system. So Post26 will display results in layer coordinate system. RSYS is not valid in Post26.
ESOL is the more accurate number to use because there is no averaging. ANSOL is a convenience tool to get average values at a node.You may want to compare ANSOL results against individual element ESOL and see if it makes sense.