Bags for life. Bags under the counter. The supermarkets might be doing their darnedest to cut plastic bag usage in stores. But for the online teams that pick and deliver, the plastic bag continues to be an Achilles heel, with Sainsbury's again the worst offender in our final Grocer 33 online survey of 2008, with 16 bags used for 30 items, two more than last time. With terrible availability and an unhelpful driver, it wasn't Sainsbury's finest hour.

"Sainsbury's makes every effort to ensure groceries are packed in as few bags as possible," said a spokesman. "Our colleagues are trained to pack online shopping bags in an efficient way, minimising the number of bags without compromising the quality of the shopping. Clearly on this occasion we have failed to do this but we hope to continue minimising these instances through ongoing training."

Waitrose used seven bags, one fewer than last time, while Asda used 11, though both retailers allowed the bags to be returned at the next delivery. Ocado delivered with seven bags, and boosted its green credentials by showing customers when the delivery van was in their area as they booked delivery slots - allowing them, if they wished, to save fuel by booking when the van was already nearby.

Of the five retailers, that left only Tesco offering crates. As a result, it required no plastic bags. However, it was let down by a lengthy log-in time and some items that were hard to find on the site.

Asda, on the other hand, provided a flawless experience and knocked Tesco off the top spot to net our Star Order award. Not only did it provide 100% availability, the exceptionally friendly and efficient driver delivered the items right into our shopper's kitchen and refused our shopper's offer to help. Although 11 bags were used, the driver clearly explained they could be returned next time an order was placed and ensured everything was to a satisfactory standard with our shopper.

Most of our shoppers managed to log on to the retailers' websites easily and had no trouble navigating them. Our Waitrose and Asda shoppers were particularly impressed with the search engines, which made items quicker to find.

Asda and Waitrose offered the cheapest delivery charge yet again, although Sainsbury's has slashed its delivery fee by £1 to £5.50 since our previous online survey. Ocado's delivery charge remained at £5.49.

Tesco, Asda, Waitrose and Ocado delivered the items on time. While the Sainsbury's driver called our shopper to inform her the delivery would be slightly early - it arrived five minutes before the allocated time slot, the driver did not help carry the shopping into the house.

Our Ocado shopper received notification shortly before the delivery informing her that the van was on its way, and informing her of the name of her driver. The Waitrose driver was described as "very helpful and knowledgable" by our shopper. The driver explained Ocado's colour-coded plastic bag system to our shopper, which she thought would make unpacking online orders quicker and simpler. He also explained the receipt, which organised items by use-by date, another feature which was appreciated.

Availability was generally high among the retailers, but Sainsbury's in particular had a number of out-of-stock items. Our Sainsbury's shopper could only order 32 of the 33 items, as it did not stock the cheese in the size we required.

When the shopping was delivered, a whopping eight items were out of stock and only six were substituted. The loose pears were replaced by a pack of six pears; own-label organic chopped tomatoes with Napolina organic chopped tomatoes, Heinz Cream of Tomato Soup with Baxters Traditional Cream of Tomato Soup, own-label strawberry jam with own-label stawberry conserve, free-range eggs with very large eggs and a 230g bar of Cadbury's Dairy Milk with two 140g bars. Apart from the pears, all substitutions cost more than the original items ordered.

The Pepsi in the size we required and the Campo Viejo Crianza Rioja were not available at Waitrose and the baguette was substituted with a flute. Tesco did not stock the bread rolls or wafer-thin ham in the required size and the McCain Home Fries came in the crispy variant only. Ocado did not stock the specific wine on our list, or the baguette in the size required, but delivered all items ordered with no substitutions. Asda delivered all 33 items.

Although several of the retailers have improved since August, others have their work cut out. But Asda's top availability and knowledgable driver coupled with a slick website made this delivery a cut above the rest.