most ergonomic rebel/zoom combo

[cactus waltz]

Hi,

I am looking into saving up for a good zoom lens for my XTi. I wonder though, which combination best matches performance with size for the rebel line. I like good optics in mid-range focal length, but I don't like it to be cumbersome. I have for example been looking at lenses like 17-40L, EF-S 17-55 and Tamron 17-50 (though without an opportunity to test them in real life).