I shoot my 24-105 f/4 L-IS on full-frame, and so for me, that is the more-versatile lens in terms of focal length range, plus it has Image Stabilizer for shooting from a moving platform, or when I am a bit out of breath or when I want to shoot hand-held at smaller f/stops in order to get deeper depth of field. And for me, the real benefit of an IS or VR lens is the ability to shoot slow-speed panning photos, and eliminate up-and-down tremors, which makes for smooth,steady,beautiful panning shots. To me, having the range from 71mm up to 105mm makes the 24-105 L-IS lens more versatile; topping out at 70mm is not really my idea of a versatile,general lens for walk-around or "one-lens" use. The 24-70 f/2.8 is designed to be pared with a second body, and a 70-200 lens. Quite often, I do not want to carry a second body and a 70-200 just to get a moderate telephoto length, and so, the 24-105-L lens is the one I went with.
Nobody can make the choice for you; the 24-70's wider aperture can come in handy for many people and some situations, so....Canon makes both!!!
Nikon's 24-85 AF-S is in many ways, a better lens for a walk-around lens than a 24-70. I still have one of those for my Nikon kit, and really,really like that range.