I have choosen the Tamron 70-200/2.8 VC because at my workplace we use the same and I was impressed by its performance and durability. We use it as workhorse and its still working- but the zoom rings rubber got expanded so its not wheater sealed for now and not very sexy.
Pretty fast and accurate AF; good built quality; very nice iq; damn good stabilization; not that pricey
Built quality not as good as Canon 70-200/2.8 also the AF slower (not significantly); zoom ring and mf ring reversed; hard to use with reversed hood