“Nginx will fail by refusing or dropping connections, Caddy will fail by slowing everything down.”
Out of the box, Nginx runs one worker and uses one core. At 10,000 clients it threw errors on 99.18 percent of requests. Caddy used three cores and never errored, but it got slow and ate a gigabyte of memory. Most benchmarks crown a winner. This one shows the defaults matter more than the server.