Ok, so I'm on a budget here and am wanting a zoom lens to mess around with. I was looking at the 70-300mm by tamron, canon and sigma. Anyone have any insight as to which is the "better" of the 3? I read a bunch of reviews and they were pretty inconclusive, other than saying the AF hunted in low light (DUH), it's a bit soft at 300mm, must use tripod in low light blah blah blah, all the stuff that is pretty obvious just by reading the specs... So what do you guys think?