It's an interesting argument with no "right" answer.
Without Steve Jobs, would we have gotten the colored iMacs, the iPod, the iPhone, the iPad, the iTunes store? Maybe. I know he is largely credited for "inventing" these things for the most part, though I'm sure for some of these he was the visionary, working with other great minds to bring these ideas to fruition.
If left to his own devices, does Tim Cook have the type of mind that could come up with these ideas/inventions? Highly unlikely. BUT, I think where Tim may be better than Steve is that he knows how to manage and create a collaborative environment where other more creative minds are allowed to flesh out their ideas both individually and with others. He knows how to leave the creation to the creative talent. He is more of a "management", numbers, facilitator type of personality as opposed to a creative and driving/ruling personality. And very importantly, he seems deeply devoted to sticking to Steve's vision of the company and the core values and mission. He seems fiercely dedicated to carrying on the tradition Apple has worked so hard to cultivate, media/Wall Street/message board talking heads be damned.
Which is better, who knows? There isn't one singular way to run a successful, innovative company, and I think we are about to find that out.