Great shots. I'm saving up for that lens as well!
I feel like I should have maybe waited and tried both the Sigma contemporary and this lens out first just to see which I prefered, since the price tag is essentially identical. But I've been really happy with all my Tamron glass.
There's a few key features of the Sigma that seems pretty nice, for example they suggest the OS is designed for panning with birding and autosports in mind (the two things I like to shoot with a telephoto). While Tamron suggests not to use VC when panning on that lens.
Then you have the 3-zone focus limiter vs. 2-zone and the additional ability to fine-tune the limits and even fine tune the focus at various focal lengths with the usb dock.