Hi
None of them is the answer!
Have a look on the description of both and also the user manuals.
Blue Kenue is a software which allow you to create the mesh, the boundary condition and also to vizualise the results. This software isn't capable to run telemac simulation
Fudaa-Prepro is a tool which has 3 differents applications but only 2 are really use (the mesh viewer is not really useful):
The POST module allow you to vizualize the results
The EDITOR allow you to edit an existing steering file, and modify the keywords value. Starting from only a geometry file, it also allow you to create automatically the boundary condition file and manage the values and generate the steering file.
It could normally also launch the simulation but this is more or less easy according your configuration. So it's easier to run the simulation directly from a command windows
Regards