[Sonata]

From what I can see, seamless-immutable basically just enforces immutability on native JavaScript data structures. Immutable.js on the other hand, implements full persistent data structures, which give much better time complexity guarantees about important operations. Immutable.js also has a rich API designed for manipulating immutable data structures and uses lazy evaluation for methods like map, filter and concat, which really improves performance when chaining chose operations.