You will do 95% of your pictures with the 18-55mm lens.
You could do the remaining 5% with the 55-250mm lens.
Many people who were raised on a point-n-shoot camera are accustom to having only one lens and tend to drift toward a lens that does it all.

But such a lens is usually twice as heavy as the 18-55mm lens, and such a full range lens tends to be not as good optically, plus it costs about the same as the other two lenses (combined) that I mentioned

The 18-135 lens happens to be one of those that is not rated as well optically.

Here is a link to Canon lenses:

http://www.usa.canon.com/cusa/consumer/products/cameras/ef_lens_lineup


If you want to see a review on specific lenses here is a European site that does a good job on lens reviews:

http://photozone.de/Reviews/canon-eos

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