From the time he was a kitten, your cat enjoyed sharpening and stretching his claws. If he tried out your couch or curtains as a scratching spot, you know how much damage it can do. Finding a good scratch pad can save your things and keep both of you happy.
If your cat could describe the ideal scratching pad, he'd probably tell you he wants something he can really sink his claws into. This means rough textures. If you look at what an outdoor cat uses to sharpen his claws, you'll find that he loves tree bark most of all. It's got a great rough texture that grabs at his claws.
Besides sharpening his claws, your kitty also scratches to leave his mark and for the pure joy of shredding something. The material doesn't have to be easy for him to shred, but if it's indestructible he won't get the satisfaction he's seeking. Look for a material he can rip up at least a little bit in a single vigorous scratching section.
A piece of wood, especially one with bark, would be the ideal scratching pad, but it can be messy and inconvenient to keep inside. Besides wood, most cats prefer sisal over nearly all other materials. Let your cat try a sisal mat or sisal rope to see if he likes it as well as most cats. Corrugated cardboard is also good for letting your kitty satisfy his urge to shred, but obviously it does not last a long time. The back side of a rug can also make a good impromptu cat scratch pad. Regular carpet isn't usually a very good material, and a lot of cats will simply ignore a carpeted scratch pad.
Besides having a textured material that your cat can shred, he also needs his scratch pad to be securely attached to the floor, wall, post or other surface. Even if it's his favorite texture, he won't want to spend time scratching it if it moves around when he goes for a good scratch. Make sure it's securely attached and completely stable.