Not sure if this is the right place for this. Moderators feel free to move.
When looking at these two lenses I see that the Canon offers IS, whereas the Sigma does not. However the Sigma is twice as fast. There are a few other differences. Cost is similar when you add the tripod collar to the Canon. Both have some great reviews; both have a few negative comments. Can anyone with actual experience with these two lenses comment?
Thanks in advance!

