It depends on what you are shooting. I'm mostly an event photographer and I use my 24-70 on a 5DMkII almost all of the time. I would love a little more range at the far end of the zoom, but I use the 24mm end a lot. Frequently at events, I don't have the luxury of backing very far away from my subjects, so I need the wide zoom capability. If there is a stage involved, I usually use a 70-200 f/2.8. I will admit that if there was a 24-105 f/2.8, I would be thrilled, but there is no such animal.