Comparison between sigma and canon 70-200 2.8 lens?

i am confused between buying the sigma APO 70-200mm F2.8 EX DG OS HSM lens and the canon 70-200 2.8 L USM (non-IS version). both are of similar price range. neither has weather sealing. but the sigma has optical stabilization of upto 4 stops where was the canon has better image quality. all these are based on internet reviews. i am personally inclined towards the sigma, but i would like some opinion about both these lenses from people who have actually used it. specially the sigma, is the quality too inferior from the canon that i should sacrifice the image stabilization instead? which would you rather buy (AMONG THESE TWO)