Choice of Lens for sports

Hello everyone,

What a fantastic website. I am new and hope to get some help on the choice of a zoom lens that I am willing to purchase. I have a 7D and very satisfied with it, however for sports photography and zoom capabilities I have been doing some research on two lenses that are in my budget. I was wondering if you can advise which one will be a better lens on the long run:
1. Sigma 70-200mm F2.8 EX DG OS HSM
2. Canon EF 70-200mm f/2.8L USM

Just for the info I live in the Netherlands where it is most the time cloudy. So when the sun is shining I am certainly outside taking shots !!

Would appreciate if anyone can advise on what you seem to be a better lens.
Awaiting your replies
Wkrgds
Levon