Which company's hardware is more stable, in case of IBM (AIX), HP (HPUX) & Sun (Solaris)

UNIX Solaris
1

Hi guru

I want to know which company's hardware is more stable means in term of H/W faults or replacement, in case of IBM (AIX), HP (HPUX) & SUN MICROSYSTEM (Solaris) & which order also, if we go through more stable to less stable system.

Regards

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rules of unix.com:
(8) No BSD vs. Linux vs. Windows or similar threads.

this is also true for hardware...