We investigate various spaces of SL(r+1)-opers and their deformations. For
each type of such opers, we study the quantum/classical duality, which relates
quantum integrable spin chains with classical solvable many body systems. In
this context, quantum/classical dualities serve as an interplay between two
different coordinate systems on the space of opers. We also establish
correspondences between the underlying oper spaces, which recently had multiple
incarnations in symplectic duality and bispectral duality.Comment: v2: 31 pages, typos corrected, references added, to appear in IMR