AVA is awesome. The fact that it runs the tests concurrently makes it very fast.
It has very helpful stack traces.

From the AVA docs
Why AVA?
- Minimal and fast
- Simple test syntax
- Runs tests concurrently
- Enforces writing atomic tests
- No implicit globals
- Isolated environment for each test file
- Write your tests in ES2015
- Promise support
- Generator function support
- Async function support
- Observable support
- Enhanced assertion messages
- Optional TAP output
- Clean stack traces