Hi All Based on your experience or existing kit, what do you think would be pros and cons of using any of following lenses on Canon 7D? Primary use: Outdoor, landscapes, food, products and people. Good walk around, single lens kit. 1. Canon EF-S 15-85 USM IS Lens 2. Canon EF 24-105 f/4 L IS Lens 3. Canon EF-S 17-55 f/2.8 IS Lens If you have to suggest only one lens which one it would be (or it is already)? Thank you as always.