Redbubble is great at returns if anything is not to your satisfaction.
Art of Where does not take returns, but if something is not right, Amy will take care of it for you. The quality of fabric is excellent, but they run small. I would suggest at least one or two sizes larger.
Excellent quality and easy returns.
Pixels is a branch of Fine Art America. There are all sorts of cool things to order from yoga mats to t-shirts which are all of excellent quality. The art prints from Pixels are exceptionally well done.
Excellence is a priority to me. When I selected printers, create patterns, or design something, I strive to make sure it is of the highest quality. I guarantee you will be pleased with the craftsmanship of every item you order. If not, Pixels and Redbubble take returns. Art of Where does not, but I will make any problem you have with them right.