Hi everyone, apologies if this topic has been done to death but a forum search didn't provide a good enough answer . I'm looking for an all-purpose zoom to be used for wedding and event photography on my 60D. Image stabilization is a must, constant f/2.8 would be nice but not essential. The cheaper the better, as I'm just out of college and still only working part time. I'd say my limit is about $600. In the past I've used the 17-40L (too slow, limited range, no IS) and Tamron 17-50 non-VC (too loud, no IS). The lenses I've been looking at are:
Sigma 17-70mm f/2.8-4 OS
Sigma 17-50mm f/2.8 OS
Canon 24-105mm f/4L IS (used)
Canon 17-55mm f/2.8 IS (used)
Do any of these stand out as a particularly good (or bad) choice? I'm a little leery of purchasing a used 17-55mm simply because they aren't nearly as rock-solid as an L lens and people tend to beat the crap out of them. I've had bad luck with Sigmas in the past but I understand they've gotten better recently.