I think in the first place will stand Cardano, in second EOS, and in third not yet created at the moment cryptocurrency.
I think it will be NEO or WANCHAIN or some of the protocol that offers interoperability. I really think that CARDANO will also be a major player in terms of protocols. During this days we cant really tell that, nobody really knows if someone just enter the protocol wars and become so powerful that ditches the other existing protocol.