I tend to think that FULLPROF is the clear favorite of the magnetic scattering community, but I have no data to prove that.
Interesting enough is the variation of the number of citations of this paper : RODRIGUEZCARVAJAL J RECENT ADVANCES IN MAGNETIC-STRUCTURE DETERMINATION BY NEUTRON POWDER DIFFRACTION PHYSICA B 1993, Vol 192, Iss 1-2, pp 55-69 In March 2001 : 441 citations in the ISI Science Citation Index, In December 2004 : 1118 citations ! Armel
