To decide, which software to be used is depends on your research model, objectives and data. Don't outrightly think that AMOS is better than R etc. If you have a good sample e.g. more than 300, have normal data and your research has a mediator--i will must recommend AMOS. So there are other factors that should be considered prior to choose software.
In other words, if you have a moderator, i will not recommend AMOS as it does not give better outputs compared to SPSS and SMART PLS.