Well I've only got two lens, a Sigma 18-200 (my first), and a Sigma 24-70 f2.8. When only had the 18-200 it had to be my all time favourite, but since I got the 24-70 it has hardly ever been off my camera.
So, from my restricted palette, I'd have to say that the Sigma 24-70 is my all time favourite.


Cheers,

Terry