I'v answered some of this with respect to Angular above. So, have a read through there for more information on that. Some of the same points apply to React. I'll re-iterate them here from that perspective:
- React is a smaller library than Aurelia, so they've got us beat on size. But, that's not entirely accurate because React is only a view engine and in most cases developers end up adding lots of 3rd party libraries together to create their homegrown framework. In this case, it's possible to end up with infrastructure code that is larger than Aurelia. Also, the developer has to maintain the sometimes tenuous connections between the libraries they have chosen. Aurelia gives you a complete platfrom, out of the box, so you don't need to worry about that as much.
- In the independent dbmonster re-paint rendering benchmark, Aurelia is about twice as fast as React. With our upcoming ui-virtualization plugin, it's almost 4x as fast as React.
- Aurelia is standards compliant; React is not. Basically, you have to adopt jsx which is neither standards compliant JS nor does it use standards compliant HTML (it has different properties and casing rules).
- Aurelia supports separated presentation patterns such as MVVM, MVC and MVP. React provides only the view layer, so you must implement these yourself. Typically, I've found that React developers don't do a good job of this and wind up not following separated presentation patterns at all.
- Aurelia is very unobtrusive. React is utterly intrusive. It uses a different language and infects the code of every component and screen.
- Aurelia is more interoperable with other libraries than React because we don't abstract the DOM unnecessarily. The closer a framework stays to standards and the more out of the way it stays, the more interoperable it will be. Usually, React developers have to rebuild just about everything. It's difficult to use jQuery or 3rd party widgets not specifically designed for React. This creates silos within the web which isn't good. Frameworks should be designed to interoperate.
- Finally, Aurelia is backed by Durandal Inc. The sole purpose of the company is to build Aurelia, its ecosystem and to support it. On the other hand, when asking a React team developer about Fracebook's committement to React they said "Facebook isn't committed to React. We are committed to some of its ideas, but not to the library." It's an open source project within FB that has no connection to their business model. It's replaceable like anything else and it's probably not up to the developers who work on it if and when that will happen.