Sigma 70-200mm f/2.8 EX DG OS HSM or Canon 70 200 f4 L IS USM

To victorian squid.

Thank you for this really helpful and detailed response.
I'm also a videographer so I considered the Sigma 50-150 2.8 OS HSM too.

But since I'll sooner or later buy a full frame camera, I stopped to consider this solution.

Jeremic