The 18-55 IS is an amazingly sharp lens for the price, and 18 mm is (IMO) about right for general purpose shooting. Much better than 50 mm.
The 28-135 isn't wide enough (again, a matter of opinion) and optically isn't as good as the 18-55 IS. As mentioned above the 28-105 is a good lens, definitely sharper than the 28-135, but not a really useful range on a crop camera.
When I got my 17-55 f/2.8 IS I kept my 18-55 IS because of its optical quality - it's sometimes handy to have a small package, and the 17-55 sure isn't small. I had a 28-135 and sold it - it overlapped with my other, better lenses.
-js
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