Is the 24-70 f/2.8 L better than the 70-200mm f/2.8 L? I don't think it is. However, the 24-70 is probably a much more useful focal range (especially when paired with a crop-sensor camera). The 24-70 is a workhorse for many, many photographers (it's not necessarily fun or glamorous to use, but it gets the job done). Personally, I wouldn't sell the highly regarded 70-200 f/2.8 (with its great image quality and versatility) and replace it with a prime that's within 70-200's focal range (no matter how good the IQ was).