I don´t have any idea about these two add on softwares for fatigue calculation. I am also new in FE simulation. Any comments or suggestions about the operating of these two softwares.
It mainly depends on what CAE package you are using. If you are using ANSYS, nCode is the most integrated. If you are using ABAQUS, then it's best to use FE-Safe. If you plan to go with non-linear FEA rather than using Neuber analysis, ABAQUS has the best solver.
I agree with Nigel. nCODE has done a better job at integrating into ANSYS WB. fe-safe can still read RST files. But you'd have to post-process in ANSYS Classic. SafeTechnology was acquired by Dassault, so it is natural to expect fe-safe to be more integrated with ABAQUS and the 3D Experience Platform. I have used both and I am currently working for DS R&D. My personal opinion is that fe-safe is more transparent, i.e., you know exactly what the software is doing. In areas like fatigue of welds, rubber, TCD, Nitinol, Infinite Life and random vibration fe-safe has the lead. Due to the influence of HBM however I'd say nCODE has more to offer in terms of signal processing.