Selection of wash buffer is depends on your matrix. I am using WGA matrix in affinity chromatography for the elution of glycoproteins and 175mM tris (pH 7.5) used for the equiliberation as well as washing buffer. 0.8M galactose plus 175mM tris used for the eution of glycoproteins.
It depends on the number, structure, and branching of oligosaccharides in each particular protein. The glycoproteins with multiple N-linked oligosaccharides might require higher molar concentrations of sugars in the buffer for elution. Please, see the general procedure from "Sigma" to start from: