Some of the softer spin friendly ones ive tried are: Volkl cyclone tour , great spin potential ,comfortable , soft to play with. Diadem Solstice (either version) massive spin due to the profile, very comfortable and soft. Yonext Poly Tour Pro , i didnt find one outstanding characteristic, but good at everything.
https://tt.tennis-warehouse.com/index.php?threads/softest-spin-oriented-co-poly.557004