I think it depends on what you like to quilt - bigger or smaller blocks? applique? I keep 2", 2.5", strings, selvages, and even triangles (future HSTs). I like to make scrappy quilts. The 2.5" squares have been useful for applique, and sometimes I use the 2" squares for appliqued circles, too. Right now I'm on a string kick, but I also have an ongoing selvage sampler in the works.