I have a 60D, what type of photography do you do? That would make it easier to recommend. I have a Sigma 10-20 uwa for landscapes and architecture, it gives great effects. I also replaced the 18-55 with a Canon 24-105 f4L as a good walkabout lens. Its not too heavy but gives great results. I just need something to replace the long end now and my choices would be the Sigma 120-300 f2.8 which is a bit out of my price range so I'll probably go for the Sigma 150-500 instead.