Ansys Employee

This is more of a general engineering question than a question directed at Ansys software. So there should be plenty of other sources that address such a material. From my basic engineering instruction, I remember that the most linear portion should deternine the yield point when it appears to start deviating significantly from this linear portion. So your second graph is most accurate, and you could use typically a multilinear isotropic or kinematic material property.

The 0.2% cutoff seems to cut off too much of the behavior's curvature.