Yes thats a very good question and it generates more question like why HEX or Algorand? It will be more appropriate if you have come up with suggestion that why to mine these coins over MASS. Like one argument in favor of MASS is that it doesnt require expensive devices and need lots of energy.
I like MASS because of some obvious reasons that it only requires HDD to start mining process. Not much infrastructure is required to start mining the MASS. I dont know much about HEX but MASS was profitable in its early days.