The only reliable software for geotechnical analysis is OPTUM G2 (for 2D) and OPTUM G3 (for 3D). They can both be downloaded from www.optumce.com. Plaxis have made a lot of noise about reliability and user-friendliness but it's mostly hot air (although they are slightly better than the likes of MIDAS and FLAC).
The Plaxis software is directed to analyze finite element geotechnical engineering problems. So you can find all the features related to such problems. Other softwares may reveal more accurate results since they contain more advanced numerical algorithms but they are designed for multi purposes one of them is geotechnical one. So it is not simple to work with these softwares such as Abacus or ANSYS.
Generally, Plaxis is used to model simple geometry problem. For complex geometry problem, you can use finite element based software like Abaqus or finite difference based software like FLAC 3D. But in Abaqus, all the features for solving Geotechnical Engineering problem are not inbuilt, for example, if you want to generate pore water pressure then scripting in FORTRAN is required.
It's depend on many factors such as which numerical method, 2D or 3D, what's your target, for research or industrial purpose, .... Generally, PLAXIS (special 2D) is more user friendly. If you want consider all element such as pile or wall for stability and interface for interaction between structural element and medium in a complex model, it is better than use other software such as FLAC3D or GTS-NX Midas. If also you want analysis the slope stability in a fractured media, you should use other software such as UDEC or 3DEC.
Plaxis is very user friendly. It is quite quick to set up your simulations compared with Abaqus, however, depending on how complex you want your simulation to be, other software such as Abaqus may be more useful.
My PhD is in slope stability simulation and I use both Plaxis and Abaqus, depending on the necessary application.
All FEM programs are not reliable and it is your responsibility to develop a valid model. You can do this by conducting understanding your problem and knowing the constitutive model which can correctly simulate the problem, conducting an extensive sensitivity analysis to find the best mesh size and model extension, validate your methodology by comparing results with experimental/laboratory results for a problem related to what you want to study.
Yes PLAXIS is a reliable software to simulate the geotechnical engineering problem mainly the slope stability problem, soil - structure interaction and ground improvement..we can do these types of analysis in more effective manner by using this software..also, PLAXIS based works have published elsewhere in various referred journals..so it is useful to do geotechnical related analysis using PLAXIS..
PLAXIS is the best one and it is practical, cost-efficient and time efficient alternative to the other FEM geotechnical programs. it is able to simulate a wide range of complex geotechnical problems and soils behaviour under static and dynamics loads.
PLAXIS is one of the most popular ones as it is easy to set up a model for a wide range of geotechnical design issues (especially for 2D) and extract some results. But I think the reliability of results has to be evaluated by the user. It is being a prevalent statement within the industry that an incompetent PLAXIS user can easily get misconceived outcomes from incorrect assumptions.
It is always good to adopt a software that has been used for sometime and its results have been evaluated by various experts. Plaxis is such a software. You will however need to understand the behaviour of soils and soil-structure interaction before garbage in gives you a lot of garbage out...
The only reliable software for geotechnical analysis is OPTUM G2 (for 2D) and OPTUM G3 (for 3D). They can both be downloaded from www.optumce.com. Plaxis have made a lot of noise about reliability and user-friendliness but it's mostly hot air (although they are slightly better than the likes of MIDAS and FLAC).
I would recommend FLAC 3D which gives you flexibility to write your codesto model the actual stress path of your problem. Variety of models available, however it is costly and requires good amount of time to understand it.