I have compared NGINX with HAProxy because both of them are open-source software. NGINX is faster than HAProxy.

We had other solutions like BIG-IP.

We also evaluated Apache but NGINX had more suitable features. 

The idea of using other lightweight solutions, or a native Ubuntu Web server, was completely overshadowed by NGINX.

No.

There were not any other real options. 

Squid is too heavy. Apache in reverse proxy mode is also over-bloated, resource hungry, and not suitable for the task.

I have evaluated many types of products that fall into this category. They are all far less superior than NGINX: F5 BIG-IP, HAProxy, Apache2, and IIS. I am sure the list goes on. 

No.

No.