Hey Gabriel, I haven't tried AppMetrics, but it looks like they have a lot of sensible metrics out of the box. You probably can't go wrong with either of them!
If you're looking for a third option, have a look at OpenTelemetry's exporters. I wrote this article almost three years ago, and since then OpenTelemetry has been standardizing metrics and observability, so it may be a solid choice, depending on what you're building.
Are you running ASP.NET?