Red Hat seems to be the top dog enterprise Linux wise. If you are looking for a "standard" linux, a RHEL compatable distro wouldn't be a bad way to go. A server I manage runs Cent OS 3.3, and is pretty nice.
Of course, if all Linux distros were "standard" there wouldn't be much of a point in having multiple distros. As it is now, users can pick a distro that is in line with their skill level and personality. That goes a long way to adoption.
Then, we have the Linux Standard Base project, which seeks to make certian things common among distros. This allows you to have something suitable to you but is also compatable with other software and distros. Here is the LSB project site:
http://www.linuxbase.org/ . And some certified packages:
http://www.opengroup.org/lsb/cert/cert_prodlist.tpl