For me, it really depends on how reliable the market is. If I know produce and fish are going to be reliably high quality and fresh, I'd be more inclined to use an online service. However, that's not really the case with the average supermarket and therefore I prefer shopping in person. (If it were available where I live, I'd probably use Instacart with Whole Foods from time to time, but I'm lukewarm on using Peapod which is available for me.)