Yes, the Sigma 105mm chart looks better. Just over simplifying the higher the line at any given point the better. I think if your comparing the Sigma vs the Sigma it might give you an idea of what to expect.

But I wouldn't read too much in to the Canon's chart vs the Sigma's because two different manufactures prepared the charts. Two different manufactures preparing similar charts, may or may not be fair comparisons with each other. With the Sigma vs Sigma you would think that Sigma arrived at the charts the same for each lens and it may be a fair comparison.