My present layout is mostly "hi-rail" so I don't have traditional operating accessories anymore. When I did have them, the re-released American Flyer oil drum loader was my quietest and most reliable accessory.
The one development that was really worrisome to me was the omni-present usage of engineering plastic gears that invariably crack over time and render the accessory unusable unless you can find a suitable replacement gear from Northwest Shortline or equivalent supplier. Lionel needs to go back to all metal gearing and make the new ones last like Postwar ones.....