The components in ExtReact and Ext JS are equivalent. If you’re already developing Ext JS applications and you have no plans to do React development, then you can continue using Ext JS. If you are planning to develop both Ext JS and React apps, then you can use Ext JS + Reactor library. If you have a team that is just focused on building React apps, then ExtReact is a great way to leverage their React knowledge and harness the power of Sencha’s comprehensive set of components.
