Welcome aboard.
Like most lens companies, Sigma has some good ones and some that aren't so good.
What is your budget?
Usually, the larger the zoom range, the lower the quality of the lens. For example, on of the best lenses for you camera, would be the Canon EF-S 17-55mm F2.8 IS. It only zooms out to 55mm, but it has a large maximum aperture of F2.8 throughout the zoom range. Also, it's a very high quality lens with great image quality. It's rather expensive though.
There are Canon 17-85mm and 15-85mm lenses, but they are both mid-range lenses in terms of quality. Not bad but not great either.
There is the Canon 24-105mm F4 L IS, which has more range but a max aperture of only F4. But being an 'L' lens, it has great quality. Also very expensive.