nginx is much more simple than full-service servers like Apache. Which is good if you want to do something easy fast (like terminate TLS, proxy, load-balance, simple redirect, simple header munging, etc.). And not good if you want to do something more complex and get into learning how nginx rewrite rules really work (totally not obvious), how if and other predicates really work (multiple articles in docs suggest it's not obvious at all) and what limitations are needed to achieve the simplicity and quickness. So if you want your webserver to do something complex, you'd go for Apache. But may still put nginx in front for LB, static content, pre-cache TLS, etc.