The best bed for your cat its generally the bed that you want to sleep in. Just find your favorite sleeping spot and that’s likely exactly where your cat wants to sleep too.
However, if you want to give your cat its own place to sleep, you might consider getting a cat bed. Such a cat bed can be a traditional bed, or something unique that gives your cat class and character, such as a ball or platform and ladder.
If you wouldn’t settle for any bed for yourself, why would you settle for any bed for your cat?