Itanium has been outselling SPARC and POWER for most of its life. It may have failed at Intel's original job (deprecate the marginally open x86 space in favour of an Itanium closed shop), but it's been a commercial success against its main competitors.
It's possible that Itanium outsold POWER but only if you ignore PowerPC which was its most successful commercialization. As an architecture it existed not only in servers but in in PowerMacs, Xbox 360, PS3, Gamecube, Wii and in embedded architectures.
