there are a couple of points i'd like to make clear. While proof of importance may seem like, POS, its not, it not only factors in the amount an account in, but also how active that account is sending and receiving xem. Also, you dont need to be a supernode to vote, all you need to have is 10k vested. In addition to this NEM also provides a unique solition to notarization/ digitization of assets through mosaics. From a dev standpoint i feel that NEM is the easiest to integrate in any application, probably the easiest API to work with