website ease of use, good quality of images with consistent relative size and multiple views on a large print, including measuring stick in the photos, some kind of help with color, like a roll-over micro-view, a design board to place fabrics next to each other, wish list in addition to cart, notice of how much is left on sale fabric, fair shipping charge and prompt shipment.
And for those times when I need to speak with someone on the phone, a friendly and knowledgeable LQS sort of salesperson.