Hello everyone first time post here and am glad to join the family to talk about photography! 
Struggling on which to choose and hope someone can shed some light or suggestions.
Given they are at a similar price range (with Sigma 300/2.8 being 2nd hand on evil bay), which lens should I get?
I am currently using a Canon 70D APSC Camera and I shoot mostly birds, a little wildlife, and a little sports (my son in soccer matches).
I am currently using a Canon 200mm F2.8 II which I love a lot but find it lacking in reach when shooting birds and wildlife.
I was thinking the Canon 300/4 IS would be the best choice but then I ran into the Sigma 300/2.8 and 120-300 non-OS on evil bay that sells around the same price as the 300/4 IS and was wondering a 300/2.8 is that much better than a 300/4 or 400/5.6.
Any thoughts?



