Well the question was which is best for A3 prints not A4  and talking from my own experiences I own a 10D as well as my 5D and have L glass lenses and thus on printing on my Canon 9100  A3 you can see the obvious benefit of the 5D over the 10D i  have no particular reason to exclude some of the other fine DSLR from the likes of Olympus and yes the range of lens from them are up there amongst the best.... However Canon do have the edge at present as regards to noise and if you are going to sell work and printing it far removed from the work seen here on Rosity at 72 dpi where images can be oversharpened  

You need to take account of the DPI pixel count to have some idea of the best possible print as interpolation will take place clearly on the 10D there  will be 3 times more so despite some prints from the 10D being stunning and good enough to sell when compared to the 5D .. They look less professional As do most digital cameras when compared to large or medium format Film prints..

I cant see how the future of DSLR lies in the hands of any one maker more it lies in the competition that may arise as a result of the improved technology in production to keep up...

If you finances are going to preclude the choice of the best you will not go far wrong with any of the current crop of superb cameras and lens on offer... Find a good dealer and makea comparison of the prints on an A3 printer not the ones they have got to show off the printer, you may see the difference then for yourself..

Danny O'Byrne  http://www.digitalartzone.co.uk/

"All the technique in the world doesn't compensate for the inability to notice" Eliott Erwitt