I have been looking at 70-200s and discussed some options in a previous thread, I will use it for rugby in daylight or under good floodlights, some home indoor use and very occasional the odd event like a wedding but not my main use. I will be using it on my 60D and also a 7D I plan to get shortly.
I can just about afford one of the following:
Canon 70-200 f4 is
Canon 70-200 f2.8 non is
Sigma 70-200 f2.8 OS
Which would you choose?