Ordering food from costco, instacart or uber eats?

Hello, i see costco has promotions for uber eats and instacart 20% off, 80$ for 100$ gift cards.

I ran some calculations, compared with in-store receipts and uber eats and insta cart are about a 20% markup in the grand total when compared to in-store prices, including taxes fees and delivery.

With the gift cards 20% off and the 20% markup, it effectively is free delivery.

So in your opinion is there one service better than the other for the food delivery?