Nikon 24-85 vs 24-120

Hi,

I recently bought D600 and thinking of getting a walk-around lens (for street, portrait).

24-85 is variable aperture but it varies only from 4-0.5 to 4+0.5. 24-120 is constant 4. 24-85 is actually faster at wide end. If I were to forego the extra range of 24-120, is 24-85 a better value? Or rather, are both these lenses similar optically in their shared range?

Thanks,

Sumit