Based on the shared experience here, the Canon EF-S 17-55mm f/2.8 IS is the stronger choice if low-light performance and shooting wide open matter to you.

The main reason is the aperture: several answers note that the Sigma’s f/2.8 is only available at the wide end and may be soft wide open, making it less useful in practice unless stopped down. By contrast, the Canon is reported to perform well at f/2.8 and become very sharp by f/4.

For your stated use—wide angle, wider apertures, and frequent high ISO—the Canon’s constant f/2.8 is a real advantage. Stabilization can help you use slower shutter speeds for static subjects, but it does not replace a faster aperture when subjects are moving. In that sense, the Canon gives you both IS and a more consistently usable fast aperture.

If budget is the priority, the Sigma may still be acceptable, but if you specifically want a high-quality fast walk-around zoom for an APS-C Canon body, the community strongly favors the Canon 17-55. A fast prime is also worth considering if maximum low-light ability matters more than zoom flexibility.