
Here's SRDs answer:
But seriously, folks....
There's an interesting issue hidden beneath the surface of this joke. It is a crucial aspect of LOTR that Gandalf does NOT "save the world". He guides and influences events in many ways; but he does not play a Covenant-like role in the story. (Shucks, he never even gets to throw down with the king of the Ringwraiths.) Neither does Aragorn, for that matter. Clearly it is important to Tolkien's intent that Middle Earth is saved by the smallest and most mundane (or at any rate least dramatic) of his characters: the Hobbits. People who consider Donaldson a Tolkien imitator should think more deeply about the differences between Gandalf and Covenant."
My mind has a simple answer (because it is a simple mind) to the "geeky" question. It's kind of like asking who can beat who, Mike Tyson (when he was actually a menance) or one of the top guys from UFC, of which I know little. All I know is that one sport has strict rules, and although knockouts are preferable, blood is considered a bonus, boxing is supposed to be a "sweet science". Not so with UFC. It's basically a slightly more sophisticated bar brawl with a referee to stop one person from killing the other.
In other words, who knows? With gloves on, standing straight, in his heyday, Tyson was unbeatable and terrifying. But could he stand up to one of the UFC champs where kicks and cheap shots (cheaper than Tyson's) ruled? Like I said...different arenas.
Also of interest, SRD makes an interesting statement regarding his comparison to Tolkien. While there are external resemblances (I won't go through the lists), there are very few internal resemblances.
Brooks, on the other hand, was a Tolkien imitator. Allanon played the exact role that Gandalf did.