Right my advice as there seems to be a huge amount of varying reviews!
Firstly, look at your budget - it was set for a reason, unless you are wealthy it is unlikely you can really be persuaded to spend above this, so that eliminates a few options.
Compare the lenses within your budget and look at things like aperture, no of blades in the lens (the more blades gives you a better or smoother background blur as it gives a more perfect circle of light in the lens, MTF charts are found online and talk about image sharpness etc, filter size etc. With this information you will start to see 1 or 2 that are strong favourites. It is then that you head to your local shop and ask them to try them out on YOUR camera. If they dont have them in ask them to get them in! This will give you a proper feel for the balance on your camera, the feel of the lens when zooming etc. Some offer internal focusing others dont, most of them the front lens wont rotate which is really useful when using a polariser or a filter system each to their own on these things!
When I purchase things I look at future proofing, the ef-s lenses are great but could never be used on a 5D if i was fortunate enough to afford one...
Best of luck and i hope this has helped in someway...:shrug: