2.8 lens for Canon 40D

Hi all,

I was wondering if I can get some advice on what lens should I buy. My main lens now is a Sigma 17-70 2.8-4.5. The lens worked ok with my XSi, but in my new 40D (thanks Canon for the big discounts :-)) I found the pictures to be too soft.

I end up using most of the time my Canon 50mm 1.8. I was thinking about changing the lens and these are some of my options:

1) EF 24-70 f/2.8 L USM
2) EF-S 17-55 f/2.8 IS USM
3) EF 24-105 f/4 L IS USM

This lens will be used as walk around lens. That means that most of the time will be the only lens that I will be carrying with me. As you can see, $1000 will be my top. I know that 17-55 gives me a little more choice but it's EF-S and I don't know if I will be jumping to a 5D in the next years.

Any thoughts?

Thanks,

BTW: I mostly shoot landscapes, some macro, buildings, city images, etc. My wife is having twins soon, so I will appreciate a lens that works also great with kid portraits

Thanks again