For local development, I don't think nginx/apache even contend against it. The config is incredibly readable, and caddy is a single executable with no dependencies.
And, having mostly worked with Rails, PHP and Python http services, the proxying webserver is hardly ever a performance issue. You can stick the slowest webserver in front of a Rails (Rack) app and still be unable to measure the latency it adds.
I've been using caddy for years and while it's slower in benchmarks, than others, I've never had the practical situation where that mattered.