Canon EF-S 17-55mm VS Sigma 17-50mm VS Tamron 17-50mm?

I need help deciding on a new better quality kit lens...

I am shooting with a 60D that I just got so I'm sticking with a crop lens to get the full wide angle that I need. Please help me pick (with evidence why) between the three lenses.

My budget is about 1000-1500$ but I also want a new Canon flash... Do you think I should go with the Canon and wait for more money to get the flash or sacrifice IQ for a third party brand? Or is the third party somehow better for cheaper? Please help never bought any third party lenses before! I am open to any suggestions, but please keep in mind I would it for everyday use (landscape/portraits) and I prefer a wide angle since I don't have any good quality wide lenses.

1. Canon EF-S 17-55mm f/2.8 IS USM Lens (999$)
2. Sigma 17-50mm f/2.8 EX DC OS HSM FLD (619$)
3. Tamron AF 17-50mm F/2.8 SP XR Di II VC (549$)

PS: I would like to use the lens for some video also... But, mostly photographs.

THANKS FOR THE HELP!