used 24-70 L vs 17-55 2.8 is usm

Hello guys

First I'm new to canon. I recieved my first dslr camera a month ago (a 7D) but I've been shooting alot with my brothers D80 and a bit with his D700.

Now I need lenses (yet I borrowed the cheepest 18-55 kit lens). I'd like a wide angle, a "walk around" lens, a tele and maybe a prime (probably 50 1.4 or 1.8 dunno yet)...I think I'm pretty sure about everything exept for the walk around one.

I first thought about the 17-40 L but I like fast apertures and the FL is pretty short. Then the 17-55 2.8 is usm for obvious reasons.

But today I went to a store where I saw the 24-70 L (second hand) for ~$1'100.

Since where I live the 17-55 2.8 is usm cost the exact same price (hood and LP-1219 included) I was wondering wich one you guys would choice.

e/ just realised I posted in the wrong section...any mods can move it ?

should posted in Canon EF and EF-S Lenses section below this section

anyhow, since u borrowed 18~55 kit, do you like that FL?
17~55mm is pretty much best walk around lens you can find for crop body
and IS helps alot when it needed.
If you want to reach bit more and can sacrifice wide angle, 24~70L is good choice, too
assuming price is same (though think most place, 24~70L is few hundred bucks more)
Gotta say 17~55mm is bit sharper than 24~70L but you lose build quality.

Well, why don't you consider a used 17-55? I think for crop sensor, 17-55 is hard to beat. If you like wide angle, take a look at canon 10-22 or tokina 11-16.

24-70 is good on fullframe, but too long on the wide end for me.

I've had both and they're very similar, if not identical, performance and IQ wise. You need to decide if 24 on a 1.6 crop is wide enough for your use. It really boils down to that as far as I can tell. I lost ~5mm going from 1.6x to 1.3x and it works well enough for my purposes, I can usually always walk backwards. I'm sure IS makes a small difference, but to be truthful I haven't noticed the lack of IS on the 24-70mm.