I moved up to an Osprey Manta 25 after shredding a normal backpack after about 6 weeks of use. Daily carry is pretty typical: change of clothes, lunch and snacks, inflator and CO2, tube, multitool, extra batteries.
One strong feature on the Manta is the 'AirSpeed suspension' which puts a ~2 inch gap between the actual bag and the mesh layer that rests against the body. This feature makes the ventilation MANY times better than a normal backpack.