Most frequently used soil models

For my PhD research on pile group foundations, I am using the advanced nonlinear Hardening Soil model in PLAXIS 3D Foundation. Although the HS model captures the nonlinear (more realistic) behaviour of soil, the more basic soil models idealising the soil as a linear elastic medium are most often used in industry.
Idealising the soil as a linear elasic medium has the effect of over-predicting pile/soil settlement thus leading to an increased factor of safety in the design. Is this extra (and often unnecessary) factor of safety necessary when the engineering profession is constantly striving for more efficient structures particularly in the current economic climate?
Vote on the poll on the right hand side and see what are the most popular soil models today.
You can also post your comments below or suggestions to soil models that should be included in the list