Both are nice, but you are comparing apples to oranges. A better comparison would be between the M60 S&W and the SP101, or the GP-100 and the S&W 686. What are you looking for: A six round, substantial revolver, or a smallish 5 round?
For carry, I prefer the M60 snubbie; for lots of shooting, the SP101.
Better yet, get both (I did). Actually, I owned all four at one time...