I'm not sure that question has an answer.
What does "best" mean to you? Most secure out of the box? Easiest to configure?
Obviously (well, maybe it's not but it should be), a box with the primary purpose of being a web server shouldn't care about eye candy etc. In other words, it doesn't matter if it's KDE or TWM. If you are new at this, it might matter to you what kinds of system configuration tools are included, but really that has little to do with the function of serving web pages.
It's a given that Apache will be the default, but there are other options. There are even distros that provide front-ends to make creating basic web pages easier for newbies; see for example the "ibays" of
There are content management systems, from very basic to highly complex, but those have nothing to do with the distro you choose.
So.. maybe you need to be more specific about what your needs and expectations are. If you are a seasoned web developer moving from some other OS, the recommendation would be entirely different than if you've never created a web page at all.
Tony Lawrence
Linux/Unix/Mac OS X Resources