Another vote for the Tamron. I have both lenses.
Pro 24-105: Smaller, lighter, 35mm extended reach and 77mm filter size.
Pro 24-70: Faster, sharper, less distortion and better VC (IS) by 1-2 stops, and the 6 year warranty.
For an everyday walk around lens, the 24-105 is hard to beat for its size, build and reach. That's why I still own it. But if IQ and versatility (2.8 for low light & stopping action) is what you're after, the Tamron wins hands down. It is a heavy lens though. Not a problem for me though, as it is the perfect compliment to my 70-200 2.8ll, which is not exactly a minimalist lens. There's really no bad choice here.