Most in the industry were certain that Apple would choose Be, whose operating system, BeOS, already ran on Apple's newest computers. Amongst Apple's other options were to license Solaris from Sun, NT from Microsoft, or to purchase a burgeoning software (it had dropped its hardware years before), NeXT.Source: Macreate
For those of you who do not know this history of OS X, and how it was almost BeOS and not NeXT, or if you didn't know that Be and NeXT was involved, this is a great article. The timeline is fleshed out well, and was a good read.
