I don't think that we can say that Jobs is worth more than Gassee.
Keep in mind that NeXT's acquisition of Apple included a lot of fringe benefits. Things like Apple's intellectual property, which allowed for the incorporation of a software compatability layer with an established operating system (Mac OS) and the use of an established line of hardware (the Macintosh); access to suppliers for hardware manufacturing; access to distribution channels for hardware and software; access to an existing customer base; and probably a heck of a lot more.
Let's also remember that Apple (under Jobs) made some mistakes. Copland had only been under development for 2 or 3 years before it was abandoned. It took much longer to whip NeXT into shape: 3 years to release Mac OS X server, and 5 years to push a consumer version of to the market. Even then, Mac OS X was considered incomplete and Apple alienated a lot of users. Things did not quiet down until Mac OS X 10.2 was released (6 years after acquisition). Mac OS X 10.3 was still introducing features that were lost in the transition (7 years after acquisition). NeXT was definitely was not a quick fix. Gassee may have been able to move BeOS into Mac OS's territory even more quickly, seeming as he already had an OS that would work on some of the PowerPCs that Apple marketed at the time.
Also keep in mind that Jobs had a stroke of luck. While the current revisionist histories point to the iPod/iTunes and halo effect as being the product of a visionary mind, it was originally created to satiate a gap in the Apple eco-system. Windows users did not gain access to iTunes for nearly 4 years, and they didn't have access to the iPod for roughly 3 years. Like I said, an Apple product for Apple customers. Even then, the desire to release iTunes for Windows (thus make the halo-effect a reality rather than a theory) was probably the result of negotiating the rights with music publishers (necessary for the iTMS).
I'm not meaning to suggest that Apple would have done as well, nevermind better, under Gassee. But I do believe that it is an awfully hard call to make because history only plays itself out one way. We can never know what would have happened in that alternative history.