...
Debian 5
Ubuntu Server 10.10
Red Hat Ent. 5
CentOS
Gentoo 10.1
Slackware 13
ArchLinux
Open Suse 11.3
Fedora 13
Madriva
for Apache, Php & Mysql?
(damn distro, i wish linux got only 1 main distro not this safari)
...
Debian 5
Ubuntu Server 10.10
Red Hat Ent. 5
CentOS
Gentoo 10.1
Slackware 13
ArchLinux
Open Suse 11.3
Fedora 13
Madriva
for Apache, Php & Mysql?
(damn distro, i wish linux got only 1 main distro not this safari)
I always end up using Debian for any "little server" installations. A lean base plus easy installs and upgrades via apt make it great for the small stuff.
You mentioned PHP. How important is it to you to have the latest-greatest PHP? If you need to stay on the bleeding-edge of PHP development you need to use a distro with a fast release cycle or you need to accept that you will be back-porting or building your own PHP binaries. For some people who are really pushing the edge, staying with the absolute newest version of PHP is very important.
Are you willing to accept that you may have to do a complete upgrade about every six months?
Do you need commercial support?
Are you more familiar with any of the above?
Do you expect that you will ever need binary packages from vendors like Oracle?
The answers to these questions should quickly narrow down your list.
Ignore the Ubuntu 10.10 suggestion. If you're rolling a server, avoid the non LTS release. I'd suggest Debian if you're comfortable with the package system as it has a smaller foot-print than Ubuntu 10.04.
If you are a newbie i suggest you Ubuntu 10.10, in the installation process you can select LAMP Server and once installed the LAMP Server is ready.
Debian is a fine choice and it sounds like you are comfortable with it so I'd recommend that. Redhat requires a subscription to patch so if you want rpm based for whatever reason CentOS is a good choice.