If I just had the budget.....

Canon EF 70-200mm f/2.8 L IS USM
Canon EF 24-70mm f/2.8 L USM
Canon EF 24-105mm f/4 L IS USM

In no particular order those would be my choices. Probably if I had to choose I will go with the 24-105, do to its weight and the IS though the other two are faster which is always and advantage no doubt.