I have solved rc mukherjee, n awasthi, p.bahadur, fiitjee packages, aakash and resonance packages and in difficulty rating i would rate p bahadur as the toughest, sometimes out of course and n awasthi and aakash pakages of the same level(6/10). fiitjee package(7/10).
rcm(8/10) and p bahabur(10/10) but only req. for olympaids.hope it would be helpful.