Walmart.com

Walmart's advantage online is the one thing pure-digital competitors can't fake: thousands of physical stores doing double duty as warehouses. That's what makes same-day grocery pickup and next-day delivery on millions of items actually work at scale, not just as a marketing promise. Add a genuine price-match guarantee and pharmacy integration, and it's the rare online store that competes with Amazon on Amazon's own turf — logistics — rather than trying to out-curate it. Less exciting than the rest of this list, more useful on a Tuesday.