Sometimes I don't know what to think of all those Camera compare reviews. For example the Sony Alpha A77 does score less than Canon 7D on DPreview. But on DxO mark the Canon 7D is positioned much lower than the Sony Alpha A77.
Canon sensors have historically been poor at color depth and DR, whereas Sony has done better by those measures (as have the Nikon bodies which use Sony-made sensors). So, it's no surprise that DxOMark rates the A77 over the 7D - keep in mind, DxO is ranking the sensor only. DPReview is giving a score for the whole camera - IQ, performance, build, etc. - and there, it makes that the 7D comes out on top.
DxO also rate the 1D4 lower than the 5DII. I am not convinced that the DxO ratings match real world experience
They rate the 1DIV's sensor
lower than the 5DII's sensor - and that makes perfect sense, given that they are close in age (1 year apart) so the technology is not too different, and the 5DII has a FF sensor. It's no accident that the 1D X uses a FF sensor...
But obviously, there's more to taking a picture than the sensor. If the 5DII's AF is inadequate for your situation, it doesn't matter that the sensor is better, all you'll have is a blurry image (with more color depth, DR, and less noise, of course, for all the good that would do you).