I haven't worked much with the "competitors" to React, but we're always looking to learn from each other and make the best tool we can. In many cases, people advertise React alternatives that are just a simplified or slightly optimized version of React – I usually don't find these super interesting; we learn more from libraries that really do something that's not possible in React which we can use as inspiration for React in the future.
I haven't worked with Vue or Aurelia enough to talk intelligently about what they bring to the table, so I won't try. When we look at what to build in React we're always just looking at how to help people build awesome apps while enjoying the process, and we try not to worry too much about the "competition". If people are already happy building apps using other libraries or frameworks, then we're happy too.