I think the Sigma lenses on the Canon mount are so bad (apart from one or two lenses) because they are reversed engineered. That is why you should always test the lenses for decentering and general sharpness at all focal lengths and apertures. Sample variance is widespread and in the end I gave up on them. From what I have seen the Sigmas do a lot better on the Nikon mount and the success rate was higher for those buyers.

Saying that I don't think it gets much better than this 19 f2.8 on the Sony E mount. Sharpness is great and the focal length suits me fine for my wide angle work. I don't think I really need anything much wider than this normally.