Sigma 70-200 2.8 OS vs Tamron 70-200 2.8 VC

I have a D7100. I'm looking to buy a 70-200 2.8. I know that the Nikon 70-200 VRII is the best, I've rented it many times but its price is quite steep. I'll shoot mostly sports and wildlife and some portraits/ fashion. I've seen few sport photographers use the Sigma 70-200 OS but I haven't seen any use the Tamron 70-200 VC. Does anyone have experience with the Tamron? I've heard the Sigma is soft at 2.8. I can't rent the Tamron 70-200 2.8 in my city therefore I can't evaluate it. Thanks for your input. I don't like buying used stuff therefore I won't buy a used Nikon 70-200 VRII or VRII.