Hi, the softwares you cited are both useful for Rietveld refinement. Maybe Maud is more user friendly, while Fullprof requires a greater effort in the preparation of the input file.
To do the refinement of what kind of data from which specimen? To be more specific, what kind of radiation do you use, do you have (or suspect) preferred orientations, residual stresses, magnetic phases, complex microstructures in your material?