I would suggest Lavaan.org. It's really a great extension package to R. Lavaan tries to copy the great, but not free, MPlus software, and even improves upon that in many ways.

Onyx is a graphical interface to SEM, which does not require to learn a script-based modeling language. It offers maximum likelihood estimation, can handle missing data and multiple groups among other features. For users who want to transition to other script-based modeling languages, Onyx supports export of graphical models to lavaan, OpenMx, and the commercial Mplus.

http://onyx.brandmaier.de

If you are interested in Path analysis having direct and indirect effects. Then AMOS would be a good option for it. Look for a registered version at the institute.

lavaan.org

Try WarpPLS but it is not free but you can test the software. It is simple and easy to use.