I was wondering which version of the Sigma 10-20 you use?

Today I noticed that while a lot of people list this lens in their signatures, some don't specify whether it is the F3.5 or the F4-5.6 ( I have ammended our signature)

We use the older one, and are very happy with it, and would rather spend our money on other lenses- but if you had your time again, which one would you choose?

Di