You don't state the body, so it's hard to be definitive.
I'll answer the last part of your question from my experience, but as I may be using different kit, it may not be entirely relevant.
I use APS-C format DSLRs, I've had an XTi, a T2i and currently a 7D and a T3i.
I've had the following lenses as 'standard zooms'
The 18-55 II. Crap. Avoid. Will only work on APS-C in anycase.
The 17-40 f4L. Great on APS-C. Weather sealed. Good IQ up until extreme corners omn APS-C. Fast focusing.
The 18-55 IS. Vast improvement over 18-55 II, and actually more versatile range and sharper than the 17-40. I actually sold the 17-40 when I got this lens because I just wasn't using the 17-40.
Currently, Sigma 18-50 EX DC f2.8 Macro. Bought for constant fast aperture (for video) useful close focus (for video) and is decent allrounder. Newer OS version is better again but double the cash. Slowish and noisy focus (not an issue for video as I only use MF) Very decent lens, very happy with it, does nice stills as well as great video.
So you'll see my emphasis on sensor type and the predominance of video. As such my experience may not be that useful, depending on your aims and body...