$19,000. The Venture offers 2x miles per dollar on your spending while the Quicksilver offer 1.5% cash back. This difference can add up over time. If you spend $19,000 in a year, you'll earn $95 more in rewards (at a rate of 1 cent per 1 mile, when redeeming Miles for travel through Capital One or as a statement credit) with the Venture.
However, don't forget to factor in other sources of value, like the 75,000-mile welcome offer (after spending $4,000 in the first 3 months), the PreCheck or Global Entry credit, and the lounge access.