The problem I have found with non L series lenses is they have been too sticky when changing focal lengths. Ok for still photography but when using video and zooming in and out the slightest stickiness comes out on the final video. I tried three different 17 85 Canon lenses and ended up getting my money back.
I like the 24-105. Doesn't give you a very wide short end, but covers a lot in a single sharp lens.
Phil
I have a 7D with 24-105 and 70-200. Bear in ming the 24-105 is IS, the 24-70 isn't - if this is an issue. Use the 24-105 for event photography with studio set-up with no problems at all and that extra bit of zoom is handy. Having said that, the 24-70 is an awesome lens. Other thing is price - 24-105 is a bit cheaper if you sniff around.