Hello, first of all, I strongly recommend to update to the current ATENA Version (4.3.0k), 3.x.x versions can not be supported any more.
For low-cycle loading, the most interesting features are Cyclic Reinforcement (Bauschinger), Memory Bond (bond model with better unloading support), and the new UNLOADING parameter in the NLCem2 material family. Some of these features are only available through ATENA Science, or by editing the ATENA Input file (.inp) in ATENA Engineering manually.

The NLCem3 material has improved confinement response (see the Theory Manual for details), however, in typical situations the differences are small compared to NLCem2 or SBETA. Please understand that in 2D modelling, the stress in the 3rd direction can not be correctly taken into account, which can have a significant influence on confinement (one has to choose plane strain or plane stress idealization; SBETA only supports plane stress).

The NLCem2User material is for special materials which can not be modelled with the standard SBETA or NLCem2 well enough, e.g., fibre reinforced concrete. Except for very rare situations, it makes no sense to spend time defining all the response functions to model normal concrete and at the end only get the same results as with NLCem2 or SBETA (or worse).

Please edit the original message instead of double posting next time (I am deleting the older one).