Canon 17-55mm f2.8 or a 24-105 F4 L

You can't really go wrong, both are excellent lenses. I do find it funny that you ask for opinions here and with about 80% saying go with the 17-55, you buy the 24-105. I've had both and love the 24-105 on a FF, but the 17-55 is what I used on my APS-C body.

There is always advice on these forums about not buying EF-S lenses because you might go FF in a year or two. My advise is buy the right lens for the body and purpose that you have right now. If things change, then sell what you don't need and buy something new that fits your new needs.

I sold my 17-55 for about 12% less than I paid for it (after three years). If I had purchased it used, and only kept it for a year, I'm sure that I could sell for close to what I paid.

As I said - both are great lenses, and I'm sure you will be happy with the 24-105.
--
Jim 'Carnac' Carnahan