Sharpness comes from many variables, and is rarely something attributed to the brand of camera. First, different manufacturers use different default settings - some like to add more sharpening to their JPGs, some leave them softer to be tuned up in post. All cameras have user customization for picture settings and can be adjusted to raise or lower the sharpening, so you can bring down the Canon or bring up the Nikon to basically deliver the same style. Shoot in RAW, and it's a non issue, as you process your own JPGs to suit your taste.
Sharpness is also an attribute of the lens used...some lenses are soft, some razor sharp. Some kit lenses are better than others.
Sharpness is an attribute of focus accuracy, and aperture setting. Are you comparing the exact same aperture, of the exact same subject, in the exact same lighting? If not, too many variables to say one is definitively sharper than another.
All of the manufacturers are so close as to be equals - Sony, Canon, Nikon, and Pentax are so close in performance across the board that the other variables - picture settings in the camera, photographer skill, quality of lens used, and post-processing capabilities - are what make the difference in the quality of the image.
Sony DSLR-A580 / Sony 18-250mm / Minolta 50mm F1.7 / Sigma 30mm F1.4 / Tamron 10-24mm / Tamron 150-600mm / Tamron 90mm F2.8 macro / Minolta 300mm F4 APO
Sony A6000 / 18-55mm F3.5-5.6 / 55-210mm F4-6.3 / 10-18mm F4 / 35mm F1.8 / 16mm F2.8 / via manual adapter, lots of Pentax K mount, Konica K/AR mount, and Leica M mount manual lenses