tcp/http monitor

http monitor is applying a simple GET that you have the ability to elaborate on. tcp:80 is only determining of the binary on the server is responding; while http monitor is inspecting some type of content (GET /r/n).

Unless you're constrained to a legacy setup, I personally will never use ICMP gateway, or TCP monitors unless forced to. Application Delivery is all about sustaining and maintaining health to your applications, and part of the user experience could be affected by liberal health monitors. IE a user browses your nginx application. The Application is experiencing a 503 service interruption, yet your TCP 80 health check has the server green because the binary nginx is ok... but the database is down.