Warcraft Lore: Who is the most powerful being?

Sargeras concept art, Wowwiki

Someone recently asked on the MMO-Champion forums, "who is the most powerful being in WoW?" Predictably, this spawned a long thread, the consensus of which seems to be that the correct answer is Sargeras. I'm not so sure. Here's my response to that thread:

Sargeras isn't the most powerful, lore-wise. This is easily demonstrated by the fact that he was corrupted by ... something. We know that it had something to do with being exposed to the twisting nether for too long, but that's all we know. There's a sort of White Wolf/Mage: The Ascension (not Awakening) thing going on in the Warcraft universe. Space isn't just an empty vacuum (or even a roiling quantum foam), but a sort of boundary layer between the worlds (Azeroth, Draenor, etc.) that we know and something... else. This something else seems to be hostile in the extreme (hence why Sargeras was off fighting to keep it at bay). We know almost nothing about what's out there, but most things in the Warcraft universe seem to have a motive intelligence, and there's no reason not to assume that that's the case when it comes to the Nether.

So... I propose that the Old Gods are a sort of cyst created by the intrusion of whatever it is that corrupted Sargeras, into Azeroth. This is why the Titans are so worried about it, not because they're unable to cope with the Old Gods directly, but because they're just the tip of the iceberg, and they can't cope with whatever lies beneath.

WoW Insider had a great article on this recently, where they speculated that Azeroth was actually a prison, built around the Warcraft universe's equivalent of Lovecraft's Azathoth (and therefore that the name similarity was a deliberate reference).

Whether that's true or no, I think there has to be a big bad planned for WoW's post-Sargeras era... and that's the only source I can see in the works.

In the same thread, someone asked about Ragnaros, and I think that topic dove-tails nicely with the above:

It's quite absurd for a group of adventurers to defeat Ragnaros, isn't it ?

Is it? Certainly, since his power nearly rivals that of the Titans (at least in the sense that he was able to champion the Old Gods against them and make some headway before being banished, though we don't know how he did this, or in what sense he went up against them "solo") I think it's pretty clear that a one-on-25 against him would likely fail. However, that was the old Ragnaros who was defeated in Blackrock Mountain due to his being incompletely summoned to Azeroth from his elemental prison. We have no idea how much that defeat weakened him. It's entirely possible that you're facing Rags at half or less strength in Firelands.

It's also important to realize that we have no way of understanding what the power-level of the Titans or their adversaries are. They're powerful, to be sure, but they also employ a number of highly sophisticated magical and mechanical systems to support their activities. Can a Titan re-shape the world with a thought, or are they merely very powerful, immortal mages with an eternity of engineering at their disposal? Would we be able to tell the difference?

If that's all they are, then measuring Ragnaros in terms of their power might be highly misleading.