I’ve been using Appsignal https://appsignal.com/
The product itself is excellent for both exception and performance monitoring, and the custom metrics are handy too. It’s also well priced too- switching over from New Relic saved us a lot of money.
I’ve pestered the Appsignal team plenty of times for help (or to obnoxiously request features!) and they’ve always been extremely helpful and responsive. Very happy with the service.
It currently has a bug where with cowboy 2 it reports 404s as errors, but that should be fixed soon.
