Americans???
Pfft...what do they know?
Empiric evidence please that Canons are in fact unbeatable for portraits and/or landscapes, and that this particular Canon provides better IQ...than... what?
D700, D3s, D3X?
Doubtful TBH...
Otherwise this is just more interweb BS masquerading as fact.
Even Ken Rockwell (sorry, sorry, I know it's a sin to mention his name), agrees that the 5DMKII provides stunning IQ, more comparable to the D3X (of course the D3X has better dynamic range and other aspects of IQ, but look at the price!).
I think the only camera the can compete with (or beat) the 5DMKII for image quality in it's price range is the A900.
Of course, it is widely agreed that the D700 has better AF and obviously shoots faster, as well as possibly being better at high ISO's (honestly, I think the two are pretty much even though at high ISO's. I've looked at multiple comparisons, and in some the D700 looks marginally better, and in some others the 5DMKII looks marginally better, so I really don't know if there is a model which is definitively (Of course, the D700 will looks better at 100%, since you're looking at a larger area than on the 5DMkII, but when scaled for the detail to match in size, the two seem to provide remarkably similar results)) In any case, the 5DMkII is certainly no slouch in the ISO department, even if the D700 beats it marginally.
Any word from the OP on which you prefer the feel of? Unless resolution or AF performance are particularly important, I'd just pick the one you like the feel of most.