There are over a dozen “button” and remote devices that have been confirmed to work with SmartThings. Some look exactly like a regular wall switch. So just depends on your own needs.
Have you had a chance to look at the FAQ yet? This is a clickable link. Each device is identified by region and whether it is wall mount or handheld, mains powered or battery operated, so read the description carefully. If you have any follow-up questions about any specific device, please ask them in the discussion thread for that device, not in the FAQ thread itself which is intended to just be one post per device. 