I am actually using typescript only for types and then passing the code (even with JSX) to babel to do all the cool stuff we know it can do. So async / await is no problemos.
But flow adds type support (same as typescript), and can also be used with babel... flow only does one thing, so better integration. Typescript doesn't offer much beyond types (and flow does that) over babel.. and as you say, you're using babel anyway.