Which webserver is better?

During past few days I have been reading about webservers available 1. Apache 2. Mongrel 3. Unicorn 4. Tornado 5. Nginx

While I have read the both Tornado, Nginx are written adressing C10K problem. Tornado being used at facebook. Twitter laying its hands on Mongrel and Unicorn and while apache serving the major percentage of Domain. My question is if I have to use one for my startup which one should it be ? Or is it completely dependent on the type of startup being founded.