Aqua Buff is a well know product in the fiberglass industry, I don't know if it's even marketed to the retail segment.
They can all work well in the right situation. Some are more aggressive than others, some surfaces need that type of product and others don't, every boat will be different, so one person’s results may not be relevant to the next person when using a product. It's more important that the system or brand you choose has several options on grit so you can use what's needed for your project, which may include sanding first.