Sigma 18-50 f/2.8 vs. Tamron 17-50 f/2.8

[McNab]

I have been using the Canon 17-55 mm 2.8 lens for the past month while my 18-200 mm lens have been repaired. Now i have to return it The Canon lens is unfortunatly out of my price range at the moment.

I have tried looking for reviews of both Sigma 18-50 and Tamron 17-50 but I still don't know which one to choose. Or should I rather save my money and wait till I can afford the Canon lens?

Any advice would be greately appreciated.

[ddr]

between the VC and non-VC versions of the tamron, the non-VC version is shaper (i owned both)

my friend has the non-OS version of the sigma and his has AF motor wear problems. the OS version doesn't have many reviews yet and cost almost twice as much as the above choices

I'd go with the tamron non-vc. they're only about $425CAD new.

to be honest though, after owning the canon, its sharpness and IS is VERY hard to give up =)
the sigma and tamron lacks corner sharpness a lot.