There are a few different things to consider when choosing the best cushion for sitting on hemorrhoids. The first is the type of hemorrhoids you have. If you have external hemorrhoids, you'll want a softer cushion so that you don't irritate them. If you have internal hemorrhoids, a firmer cushion may be more comfortable.
Another thing to consider is the shape of the cushion. Some cushions are designed to fit specific chairs, while others are more universal. If you have a specific chair that you use most often, it might be worth getting a custom-fit cushion. Otherwise, look for a cushion that will work with any chair or seat.
Finally, think about how often you'll be using the cushion and how easy it is to clean. If you plan on using it every day, choose a machine-washable option. If ease of cleaning is your top priority, look for a disposable or wipe-clean option.