1DX definitely. Not because it's simply the flagship due to it's naming. But simply, if you've used it, you'll agree that it is really that good. On paper it may not be much from the 1D4 like how people thought 5D3 is not much of a difference from 5D2. But until you've used it, you'll realize it's different from 1D4.
These are the more prominent photographic products from Canon in 2012:
cameras: G15, G1X, EOS-M, 650D, 6D, 5D3, 1DX, 1DC
lenses: 40mm f/2.8 pancake, 24 f/2.8 IS, 28 f/2.8 IS, 35 f/2 IS, 24-70 f/4 IS, 24-70 f/2.8
I think the technology (pulling high quality stills from video) in 1DC is going to be deemed revolutionary in time to come. As for lenses, 40 f/2.8 pancake gets my vote... only because it's the first pancake lens ever from Canon... hope there'll be more soon.
Canon is certainly on the right path in 2012. If they can get their 0.18um wafer fab ready in 2013, that will be even better.