I have been using the Shielding_LEND physics list for photoneutron studies <= 20MeV. Neutron production rates, where I had data for comparison, were of the same order of magnitude as experiment, but spectral shapes were not a good approximation to reality. (See photoneutron process is inaccurate at low gamma ray energy.) I tried three other physics lists (QBBC, QGSP_BIC_HP, Shielding). They had the same rates and spectral shapes as each other, which were different from those of Shielding_LEND. However, their rates and shapes were no closer to experiment than Shielding_LEND.
So in short, for me it’s hard to say what is the best choice. I’ll let the experts jump in this one.