Basically I make a choice not based on OS/IS.
But what I found now, Sigma's late lenses mostly are great performer and worth for money.
24-70 f2.8 HSM, 50-150 f2.8 HSM, 30 f1.4, etc, etc
(PS: a guy in CP said, if Sigma/Tammy coloring their lenses into white, sure will boost their sales in Canonian realm, but most likely Nikon/Sony/Pentax will despise them)
time to take serious look on 17-50mm to replace my non VC tammy with good optical stabilizer, i think i will have more easy time shooting sharp pic with my shaky hand wahaha