Switching to the Dark Side

After a month and some odd days...I have returned.
Im glad I made my promise about the camera I would enjoy to have.
Now im debating between:
Sigma 24-70mm f/2.8
OR
Canon 24-70mm f/2.8 L

Please give me some input.

It's funny that when I opened this massive thing today Carmina Burana popped into my head. HAHA