onick wrote in post #11478016
70-200mm f4l is certainly sharper, and with more contrast and color but doesn't have image stabilization, so you have shoot at a high shutter speed to avoid getting blurry picture.
Or you can follow the advice of many professionals, and use a tripod. Lets face it, i would not call the 70-200 focal length to be a casual walking around lens, especially when it is put onto a crop camera.
IS doesn't do anyone any benefit if the subject that you are shooting is moving. If you are getting a longer lens just to round out your collection, then you might consider yourself on the slippery slope. When are you going to add in the Macro Lens, and the ultra telephoto not to mention you must have the Ultra Wide Angle too.
I'd start of by asking yourself what you are planning to shoot with this lens. And also consider what other equipment would be just as important. Like a good tripod. A remote cable release. A good flash.
Personally I would go with the 70-200f/4 as it's an incredible lens. This will open up a whole load of other shooting avenues to you and is one of those lens that you'll keep a lifetime as they honestly don't come much better.
matt.