I own several Sigs and I own a 225 and a 239 in .40.

I beleive the 225 to be the best feeling single stack made. It fits my hand perfectly, and is as accurate as I can shoot it. Its rock solid and it looks good.

The 239 is good, but it feels a lot heavier. The trigger is great, it has the smoothest, lightest double action trigger of all of them, but the 225 seems easier to carry.

A size comparison of the two.