Thanks to OPENSAP I've had the oportunity of getting knowledge about this two different technologies.
In a nutshell, Sap screen Personas has the purpose of making SAP users lifes easier while using the same ERP CRM transactions they are used to.
On the other hand, SP FIORI proposes a new paradigm which integrates old and new technologies, leveraging the power of SAP HANA, in order to create powerful en user applications across different platforms.
Since both approaches have different purposes, is logic to ask the question.
Which of them suits better you current requirements ? Which one will you start to implemet first and from which one will you obtain the bets benefit ?