fyi to anyone seriously considering using these: neither is going to work as expected if something blocks the loop indefinitely. In other words, you won't know how long something blocked the loop until that thing has finished blocking. Timeouts for async code or limits on loop statements are still relevant.
If something is blocking the eventloop indefinitely, it's unlikely to reach production and even if it does, a simple crash report or perf inspection will reveal it. You don't need more tools than node-report for that case.
Permanent eventloop block is the simple case.
Regular eventloop blocking by synchronous processing is the middle ground.
Performance issues with utilization of resources, too many promises or broken backpressure - that's where the fun begins.
If you can run your software locally and simulate load, just use node clinic. It's the best looking one ;)