i wouldn't say that if i did not compare them myself. i did that on a 70d and found the sigma to be significantly better. not just pixel peeping but it was noticeable at full size. in fact the sigma on a 70d is comparable to the the canon on a 5diii, and the sigma is f/1.8 which is really important on a crop body.
You may want to refer instead to Roger Cicala's tests. They are more credible since he's using more samples than anyone can afford.